as far as a percentage in their demographic your right, a higher percentage of gay men have probably had anal sex in the gay male community. but you have to remember there are way more heterosexual men than homosexual men. rough estimates are that 5% of the male population is gay. so even if only 10% of heterosexual men have had anal sex with a female partner, they will still outnumber the total number of homosexual men that have had anal sex.