As far I know 1, me 20-30 years ago, neither of us enjoyed it. Anal is off limits, yeah a guy can touch her anus, but that's about as far as it goes, she's really not submissive and will let a partner now when he's gone too far. I've tried to rim her but she stops me.
I tired once but the guy was way too big, I am open to try again with the following criteria: small, dick, plenty of lube, condom