I believe it's more than 80%. Pooning happens for all kinds of reasons, sometimes it's loneliness, others it's just the thrill. I have one good friend that knows what I do and I know that he does it too. I am primarily a R&T guy, and have only ventured into FS on a number of occasions. I have given him some good recommendations as he's not on this board. He's in a relationship and it's pretty solid but apparently he doesn't see much action at home (his SO is a workaholic and travels a lot for business). I have another friend who goes to massage girls with some frequency and has no problem letting everyone know. He has a Thai wife who is aware of this and seems to look the other way. I don't talk to him about it because he's a bit of a loudmouth.
In short, it happens a lot more than anyone lets on. I'm sure if any of the ladies on the board want to chime in on this, they would probably agree. I had my favorite R&T girl who I saw regularly for years. She knows a lot about my private life and could probably write a book on her clients with all the dirt she has. Sort of like a bartender or hairdresser that you see on a regular basis. She says she could always tell when I started seeing someone, but always happy to see me come back. And I don't doubt for a minute that some of my buddies have seen her as well...