Had an hour to kill so I decided to pull current data on SB profiles in my local area. I last did this in December (published here in April) and again early April (not published). So I'll show how numbers have changed since April 7, 2020 for my location, as of August 5, 2020.  
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A few notes to set the stage:  
1. Criteria for search was based on radius, ethnicity, and age.  
2. Radius from my location in the San Fernando Valley (north area of LA County, bordering on Simi Valley/Ventura County to the west.) used are 25 and 10 miles, centered on my Zip/City.  
3. Ethnicity was all categories in the SA search filter: Asian, Black, Latin, East Indian, Middle Eastern, Mixed, Native American, Pacific Islander, White, Other.  For ease of consumption, I rolled up ethnicity to Asian + Pacific islander, Black + Mixed, Latin, White, All Others (Other, East Indn., Native  American).  
4. Age broken down by Max=18-38, with sub criteria at 18, 19, 20, 21, 22-23, 24-25, 26-28, 29-30, 31-33, and 34-38. For ease of consumption, I rolled up age to 18-20, 21-25, 26-28, 29-33, and 34-38.  
5. Note: No filters used for last date active. So these numbers include all profiles that come up in search, regardless of last active date.  
6. Note: This is data for my market only, I did not look, and do not intend to look, at any other areas. So please keep that in mind as you compare my local results to your market. Los Angeles county is HUGE. If I had changed my search center by as little as 10 miles south of me (closer to Downtown/Central/West LA) the number would probably be substantially higher - which should blow your mind when you see how many profiles I counted.  
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Top Findings:  
1. As has been widely speculated here, total number of profiles has risen dramatically Since April, 7:  37, 560 in April, versus 51,074 today, a 36% increase.  
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2.  Most of this growth comes from Latina profiles (up 144%) and age 18-20 profiles (up 58%).  Although there is an increase in number of profiles across all ethnic categories, and in all age categories.  
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3. The  ethnic "mix' in August is has changed only slightly from April, with Blacks moving up to #2 and Latin moving down to #3, while White remains at #1.  The three largest ethnic groups remains White (32.45% now vs 32.49%), Latin (28.16% vs. 26.54%), and Black+ Mixed (27.66% vs 29.16%). Asians (including Pacific Islanders) remain the 3nd lowest represented ethnic groups (6.15% vs 6.27%) and All Others (East Ind., Middle east, Native Am., Other) remains the lowest represented ethnic group *5.57% vs 5.53%).  
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Here's the Summarized Ethnic at 25 miles data:  
                                          Comparison vs Last Check
Ethnicity     # In Grp        % Grp  # Change  % Change
Asian + PI          3,142     6.15%     787         133.4%
Black + Mixed  14,129     27.66%     3,177       129.0%
Latin               14,382     28.16%   4,412     144.3%
White               16,574   32.45%   4,369     135.8%
All Others          2,847   5.57%     769         137.0%
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Total               51,074     100.00% 13,514   136.0%
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Here's the summarized Age at 25 miles data:  
                                 Comparison vs Last Check
Age         # In Grp % Grp      # Change      % Change
18-20 15,422   30.19%   5,662     158.0%
21-25 23,453   45.92%   5,990     134.3%
26-28 6,311     12.36%   1,033     119.6%
29-33 4,467     8.75%     594         115.3%
34-38 1,425     2.79%     231         119.3%
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Total 51,078   100.00%      13,510       136.0%
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I've had pretty poor luck posting tables here. So If you would like an excel or .PDF version of this, DM me with an email address and I'll send the file.  
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Because....  
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Life is good
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The Cat

-- Modified on 8/5/2020 4:23:28 PM

I just ran the same calculations for my area and I used the same search parameters as you did with one exception.  My search radius is 100 miles, not 25.  It's the only way to include the University town that's about 55 miles from me and provides the majority of SB profiles.  My total number is a paltry 3091, only about 6% of the numbers you are working with, you lucky dog!  Plus, my normal search is more restrictive.  I use 18-35 for age, and further restrict my search to only include slim/average/and athletic body types which brings my search results down to 1551, just 3% of your 51 thousand! Pre covid my search consistently resulted in about 1100 hits. So I'm seeing a 41% increase in profiles overall, roughly the same as your results, although the numbers themselves are tiny by comparison.  Here's my current results, I don't have saved data to compare with:

Ethnicity     #in grp    % grp

Asian & PI           39     1.3%
Blk & mixed     472    15.3%
Latin                1440    46.6%
White                 920    29.8%
All others           219    7.1%
total                  3081    99%

Age               #in grp    %grp
18-20                887    27.8%
21-25              1334    43.3%
26-28                 351    11.4%
29-33                363    11.8%
34-38                146    4.7
total                3081    100.1%

Findings and observations
1. As I stated above the numbers have risen about 41% overall which is huge. Although I don't have an ethnic breakdown, my seat of the pants feeling is that the increase is fairly consistent across all ethnic groups and concentrated in the lower age categories.

2. Top ethnic group is Latin with nearly 47% and White firmly in second place at 30%.  These two groups account for over 76% of the total in my area which is historically Latin with a very small Black population.

3. The overall numbers suggest that I live in Pussy Siberia.  Maybe it's not a fair comparison since obviously Herb lives in Pussy Paradise.  SA is my only source of female companionship since there are zero worthwhile pros or Kgirl agencies here. Yet I manage to enjoy a success rate which is more than adequate for my needs, desires, and appetites.  Some might say that this proves I have exceptional Sugar Game!  The reality is that even with a target poor environment, you only need to find a few good SB matches to be a very happy SD indeed!  

Very interesting to see that age distribution is essentially the same in each market.  Can we draw any hard conclusions about this such as "SA has become a viable alternative to unemployment for women between 18-25 years old during COVID"? Probably not. But I think we can use that as a reasonable assumption for now.  
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And given the lower level of black's in your local population, I'd say ethnic distribution is reasonably similar between the two markets as well.  
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So given these data sets, does anyone feel they need to change their strategy for searching, contacting, negotiating, or sustaining an arrangement?  
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I really have not, with the possible exception of doing extra verification of pics and contact info when provided, along with being open to a virtual M&G with no sugar. I have also started initiating contact more with certain POT's, mainly hot Asians. Note that I generally never initiate contact.  I prefer to let the POT message me 1st. Sadly, my attempts to initiate contact have not delivered any good results.  
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After all, as Pappy Sweet points out (you didn't think I'd let that moniker fade away, did you Pappy? , even a relatively small market can yield good results...if you have decent game.  
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BTW: For my new POT searches, I also use more restrictive filters. I used the more open criteria noted in my post specifically for sizing the overall market, with the exception of POT's 39 and up (because I'm not interested in MILF's or GILF's).  
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My standard search criteria is:  
Radius: 10 miles
Age: 18-38
Body: Slim, Athletic
Smoking: No  
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This generally yields about 870 results. Note that around 150 of these were active within the last 5 days - which is about as "stale" as I'll accept. When I don't see a lot of new profiles in the last few days, or I'm not happy with anything in the 150 (out of the 870-ish), I add body type Average, which usually increases my yield to about 1,200 results, with around 250 active in the last 5 days.  
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Do I live in Pussy Paradise? I don't know... but I do know that...
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Life is good
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The Cat

I live really close to DC.  To accurately assess my target pool, kept in place my normal baseline screens (eliminated non-drinkers and smokers, max height 6 ft, slim to curvy included.  Also eliminated profiles that contain the words: platonic, marriage minded, monogamous, and trans anything).  In addition, as I search the SA site daily, I have "hidden" a fair number of profiles that pass my screening, but that I no longer want to see.

Within 10 miles, 5163
Within 25 miles, 7217

Used 25 miles to search by age and ethnicity.

   Asian         Black             Latin     East India.   Middle East    Mixed     Native American
298(4.1%)   2198(30.5%)      946(13.1%)   22(0.3%)   89(1.2%) 1156(16%)  50(0.7%)                            

Pacific Islander White           Other
  43(0.6%)            2194(30.4%)       220(3%)

18-20 1228 17.0%
21-25 3566 49.4%
26-28 1210 16.8%
29-33 898 12.4%
34-39 316   4.4%
      7218 100%

During my analysis 1 person joined which is why the age total is 1 greater than the ethnicity total.

Findings:
-Numbers of Blacks and whites are nearly identical
-Kept mixed separate from Blacks.  Clearly many are biracial (Black + xxx), but DC is such a melting pot, that many of the mixed also have no Black ethnicity
-Mixed and Latino nearly identical in 3rd and 4th place
-Half of my target population 21-25; whereas my favorite demographic (26-28) only represents 12.4%

How will I use this data?
Not sure.  Having so much fun and success that I will continue to use the techniques learned on this board.  Perhaps, I'll go back into the 21-25 age group since it represents nearly half of my overall targets.

Thanks for pulling the data for your area. Very interesting results.
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I did not include data for a radius less than 25 miles in my original post. In my area, the percentages by age and ethnicity are about the same between the two distances (10 and 25 miles). But I should add the the number of profiles at 25 miles, about 51K, drops to just 2,550 at 10 miles. So I'm only seeing about 5% of the total 25 mile market.  If I expand my radius to 15 miles the total number of profiles doubles to about 5,700, or about 11% of the 25 mile group.  
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The problem with extending to 15 miles in Los Angeles is that those last 5 miles usually almost doubles travel time, from 15-30 minutes to as much as 30-75 minutes, depending on traffic, and specific location.  
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So my local "pond" remains relatively limited (relevant to LA) to the 2,550 within 10 miles. But fortunately for a nice, old, fat guy like me, that still enables me to tap as much 18-25 year old SB pussy as I can handle. And I can and sometimes do, expand up the age scale to include SB's up to 38. The oldest SB I ever had was 37, Asian and fucked like she'd never see dick again. Too bad her "kid baggage" ruined the arrangement.  
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How do you use this data?  That depends on what you want to accomplish, I suppose.  Do you change your search criteria to focus on the more populous demographic groups? Do you rewrite your profile to attract more of your preferred group?  Do you change the way you message (writing style, use of slang, contemporary references, comms tools/apps to be more user-friendly to your target group)?  Can you infer better why she's on the site by aligning her to a certain group? i.e.:  Why don't we have more Asians? Possible answer: Asians make up about 4.8% of the DC Metro area - according to Wikipedia. So they are only slightly under-represented on SA at 4.1%.
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Please experiment a bit and report back. Because any time you can take an SB BCD...  
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Life is good
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The Cat