Great question, let me try helping you on this one.
Well, it's not a secret that females, in general, live longer than males. This means that as people reach older age, males start dying few years earlier (of course, both genders die at different time; however, statistically saying, men do start dying earlier)
This leaves us with one possible answer - 75-80 years old since this is the average lifespan of a human being.