Many of my friends in the transgender community are heterosexuals. It sounds somewhat strange to people who haven't thought it through, but you can be hetero and gay. Also "dabbling" or experimenting with bisexuality doesn't make you gay.Most people suggest that one out of ten men is gay. This of course is not verified, but is a general belief.
Last survey I saw, which was admitedly 20 years ago, put the figure at 1 in 16, but not 1 in 16 people as gay but 1 in 16 either identified as gay/bisexual or had had a sexual experience with a member of the same sex.
As was mentioned up thread, being gay isn't (solely) about your sexual practices.