I don't know the percentage of all providers. My experience is about half of the ones I've seen will allow CIM (cum in mouth).

don't think anyone else does either.  If she does not do BBBJ, I don't see her.  CIM is a bonus, but not required for me.  IMHO, it's just the provider's personal preference as to whether she will allow CIM.  I don't worry about her reasons one way or another, it's not really any of my business anyway.  Some actually like the taste, but I have never asked why she does or why she won't do CIM.  One did tell me my cum tasted sweet.

Swim

the chances of STD are fairly low.  Both saliva nad stomach acid kill bacteria and viruses pretty effectively.

I'd say about half the gals I see will swallow cum, and some actually insist on it.  Fine with me

What percentage of providers let clients finish (don't know what words I am allowed to use here) in their mouth, (without a condom). I would think this is very risky, but maybe some provders take the risk or don't think much about it? Or have this notion that saliva will kill anthing bad?

I almost always choose providers who do BBBJs to begin with. There is reportedly a slight risk for giving a BBBJ.  I've never heard of any reports of increased risk for CIM.

Agreed with all the above.  If I'm seeing a FS provider, I want BBBJ with CIM.  CBJ just isn't the same; and if I can't CIM, I'm constantly aware of the fact that I need to warn her before the moment of truth (though experienced providers can feel it coming, so to speak.)

Swallow or spit doesn't really matter to me.  It's a bit of a distraction if she leaps up and races to the bathroom; but by then I'm lost in a post-orgasmic haze and really don't care all that much.