I notice that the statistics are based on self-reporting.<quoted text>
So? There are plenty of heterosexual men that would LOVE to be able to get that many women into bed with them. The only thing stopping them is that they need to get women to say "yes". With gays, there is a feedback loop going where you might have both partners more interested in casual sex and promiscuity.
Women are far less likely to want promiscuity.(There are exceptions.) Heck, there are far too many places in this country where a girl can get raped and still be labeled a slut - even if she was drugged to the point of being unconscious.
Bias is not even considered, nor lifestyle.
When an activity is marginalized it's bound to go underground as in a sub-culture of prostitution.