People joke about the 41% because it's obviously, patently absurd.
Estimates are that 150,000 teenage children (13-17) in the US are
transgender. If, as studies
show, around 40% of them have attempted suicide by age 19, you'd expect 60,000 suicide attempts out of that population. With one completed suicide estimated from every 25
attempts, you'd expect 2,400 trans youth suicides in the 13-17 age cohort over the course of four years, an average of 600 per year.
However, only ~6000 people commit suicide each year in the entire 15-24 cohort. In the 15-19 cohort the number is even smaller: 10.5 per 100,000, or 2,205 suicides in the population of 21 million children in that age
band.
What they're saying is that 25% or so of the children who commit suicide every year are doing so because they are trans. Two every day. Where are they? Nobody knows! But we're all supposed to believe their suicide attempt numbers, and not believe that maybe some kids are fibbing for attention about how serious they were with that butter knife.
All trans suicide surveys are done with shady methodology that doesn't confirm the suicide attempt was serious, and trans surveys typically ask about lifetime attempts (which people are notoriously worse at being truthful about, as "I was down for a while and thought about suicide" becomes "I totally tried to kill myself but the cat stopped me" later on) rather than attempts in the last 12 months. They don't ask whether the attempt required hospitalization or anything like that, because it'd become obvious that these are fakers.