T-Girls' Whereabouts

[Vanillas]

I gather from most of the posts I've read on this site, and from the "live session" advertisements that pop up, that Thailand and the Philippines have unusually large populations of T-Girls. And, from other sites I get the impression that Brazil also has a rather large number. Does anyone know if this is true? Do these three countries have significantly more T-Girls per capita than any other country? And if so, Why? Surely its not something in the water.