Gay men have the most sex partners, right? Actually, they come in a distant third. Using General Social Survey data, I calculated the mean number of sex partners in the past year for people 18-30. (It's not precisely the mean since the highest estimates were assigned lower numbers--dumb, I know, but I didn't design the damn thing). Here are the results:
Mean number of sex partners in the past year
Bisexual men 4.50
Bisexual women 3.83
Gay men 2.54
Straight men 1.93
Straight women 1.43
By far, guys who swing both ways have the most partners, and I'm amazed that women of any stripe beat gay men. On the other hand, I'm not surpised to see lesbians (and straight women, of course) on the low end. Overall, the numbers might be lower than you would expect for young people. My thinking is that we get a distorted view of the frequency and prevalence of this kind of behavior from the media. Life isn't as wild as depicted on the screen.
If we look at those on the extreme end, the promiscuous gay man appears:
Percent with 11-100 sex partners last year
Gay men 9.3
Bisexual men 7.1
Bisexual women 2.9
Straight men 2.2
Straight women 0.3
Evidently, there is a small group of homosexual guys who conform to the stereotype of many, many partners, but this does not appear to be the norm. It's unheard of for a lesbian to act that way (showing once again that lesbians are not like gay men), and rare for a straight woman--the 0.3 percent might be prostitutes. Oh, come to think of it, some of those gay and bisexual men might do it for money too.