Though I am not sure if there is accurate information in this regard,
the perception is that the percentage is high. However, the word
"transgender" covers a wide spectrum of people, including
transsexuals, shemales, crossdressers, transvestites, drag queens,
t-girls, gender queer, to name just a few.
From my own experience in the trans community, my perception is that
the majority of sex workers fall into the shemale category.
Crossdressers have a higher percentage of heterosexuals, and outside
of thier crossdressing moments (days, weekends, etc) live quite
"normal" traditional lives. Some transsexuals work in the sex trade
to finance thier gender operations. But these transsexuals are
entirely different of mind than the shemales that have no desire to be
complete women, and seek out the sex trade by choice, not
In any situation regarding the transgender community you will find
extreme positions, most of it opinion, and most of it formed from a
narrow view. The trans community is diverse, and it a mistake to try
and box the entire community together.