I suspect the percentage of gay crossdressers is more or less the same as in general society. However there seems to be a higher percentage of bisexual crossdressers than in general society.
One problem is that CD’s have a few excuses that they often use. I’ve heard. “I’m not bi as when I have sex with a man I’m presenting as a woman therefore it’s straight sex.” Also “I’m not bi because most of the time I have sex with a woman and only sex with a man once in a great while.”
It’s also true that some CD’s enjoy sex with another CD but would not want to be with a man if they did not dress too.