i think it makes more sense to split it into thirds: for example in germany, for biological men, its 78 year, meaning you enter your middle ages at 26 years old and your old age at 52 years old. For biological women, its 83 years of life expectancy, meaning you enter your middle ages at 27.6 years old and your old age at 55.3 years old

edit: didn't mean to cause a gender debate, i dont think the statistic acounts for trans people, which i don't agree with. i would be curious to see the life expectancy statistics of trans conpared to cis people. i would guess cis would have been a better way for me to say it because i would think official statistics would go with your "official" gender but idk