There are more lesbians, but not more gay men now: For this decade and the 1990s, I compared the percent of American men and women who said they have sex exclusively with members of the same gender (GSS data):
Percent who are homosexual (N = 17,295)
This decade 3.6
This decade 2.5*
* p < .05, two-tail test
While homosexual prevalence went up for both sexes, only the lesbian increase is statistically significant.
Acceptance of homosexuality also increased significantly over the past two decades. The percent of Americans who feel that there is nothing wrong with homosexuality rose from 23.6% in the nineties to 32.5% in this decade.
With the growing acceptance, why didn't the number of gay men increase due to a greater willingness to admit it? And if willingness to report is not a factor, perhaps the growth among lesbians is real growth and not just a change in being more honest. I take this as evidence that female sexual orientation is flexible enough to be influenced by social acceptance, whereas male homosexuality may not be. As American society continues to embrace lesbianism, we might get more of it.