first of all, you need a source for 400. 2nd of all 400/11000 athletes is 3%. that's roughly inline with population statistics in the 15-25 demographic
Here's a helpful map of cultures with transgendered subsets that are accepted in society. Cultures on every continent have a deep historical record of transgendered folks.
No its not 3% for the world, for USA maybe but most countries barely have any trans people at all.