Well but 50 makes sense though you are kinda useless in your first 20-25 years then you start working acquiring experience etc 25 years later you are in the middle then 25 years later you die
If I understand this correctly, it's life expectancy at birth, right? So if you read this, the relevant-to-you life expectancy is even lower. Though AFAIK you also get a "bonus" for still being alive, so it's probably a wash ...