the number of measured sinister people (as in, left-handed, that’s where the word comes from) were rising like crazy too when it started gaining cultural acceptance that maybe, just maybe it’s not evil that you use your left hand to do things. it was like a whole epidemic, sinister people started popping up left and right.
…and then it plateaued at a flat 12.5% and stayed there since. turns out that’s just the biological occurrence rate, but everyone was under-measuring it because people weren’t willing to own it up that they’re left-handed.
trans people are the same. you get different amounts of persecution for it between different time periods and different regimes, and you get different levels of acceptance in different age groups, but the level of persecution is not zero anywhere. it’s not as normalized as just being a lefty. as such, the measured number of trans people is below the real amount in all of these situations, and how much below it is represents the amount of repression and persecution. we’ll get accurate numbers for the occurrence rate of people born in the wrong bodies when the stigma is gone.
also, you seriously misinterpreted the medical issue. the issue isn’t with the brain, it’s with the body. you’re not a pile of muscle with some neurons slapped on top of it, you’re a brain piloting a meat suit, and if the meat suit is the wrong kind that’s what needs to be corrected. and that correction is much easier to do before puberty than after. which is why you need to listen to trans kids and at the very least give them puberty blockers, or preferably adequate hormone therapy. but you can’t “prevent” trans people unless you can detect and fix the issue in the womb.