Do transsexuals more commonly have a sexual preference for the original or new gender?

I just had this discussion with my sister, but I couldn’t find any statistics/research on this, so I was hoping Fluther knew of some. If a person has a sex change, is it more common for him/her to have a sexual preference for people of his/her old gender or for his/her new gender?

Note that I don’t discuss transsexuals often, so if I made a mistake in terminology, my apologies (and please correct me).