Как рассчитать счастье человека.

def happiness_level(age):
    if age >= 0 and age <= 20:
        return 80
    elif age >= 21 and age <= 35:
        return 70
    elif age >= 36 and age <= 50:
        return 60
    elif age >= 51 and age <= 65:
        return 50
    elif age >= 66 and age <= 80:
        return 40
    elif age >= 81 and age <= 100:
        return 30
    else:
        return None

age = 91
happiness = happiness_level(age)
print(happiness)