Because I find the whole "underground economy" aspect of this just fascinating. The SA world is interesting for this type of analysis, because we have some notion of both endpoints in the equation: The number of nearby women who COULD do SA, and the number of nearby women who DO.
There are some complications:
(1) SB's are transient so if there are, in Sweetman's analysis, 1.8% of the potential SBs who are actual CURRENTLY SB's then the total %tage is even higher, because the current results on the SA site don't capture those who tried it and quit, or those who have yet to to try it.
(2) I've run similar numbers, more often just using the college girl population nearby and come up with estimates for 0.1% to 1% who are on SA. My experience with several(!!) girls from a local college sorority seem to indicate a high level of awareness of SA and a high level of participation too.
(3) And in opposition to point #1, I know for sure that some SBs have used multiple profiles, so this tends to lower the %tage of women in actually participate in the Sugar bowl, because we're double (or triple, etc) counting those who do.
(4) and there is the interesting flip side to this: Of that nominal 1M population near Sweetman, 50% are male, so what percentage of those males are on SA, looking for SBs? I don't have any good numbers on this, but the answer for my immediate locale (small town of 75,000) is REALLY low, something like 15! So, the math, 70,000/2=35,000, cut that a bit for say, ages, 40-70, so maybe 20,000 and the SB percentage is something like 15/20,000=0.08%.
(5) So, it appears that, around my town at least, there are lots of SBs for every SD. How many? At least a few, and possibly as many as 20. This is in sharp contrast to the escort world, where it is very clear that there are many more hobbyists than providers. This disparity between those two worlds likely accounts for the differences in behavior (much longer dates, sometimes aggressive solicitation and pursuit of SDs by SBs) and the lower prices.
(6) A big conclusion is that the escort/hobbyist world, enabled by the internet, is now being disrupted by the internet. The famous word in internet commerce is "disintermediation" and it is happening again: Centralized sites and third parties like TER and pee four, etc, are being cut out by a direct SB/SD connection.
Sorry for the PhD thesis, but this issue has always interested me, and another big conclusion is that things are now good for guys pursuing these women, and are likely to get better over time.