Yeah, 16 is too young. Also illegal in most countries.
In their early 20's they are in their biological and attractiveness prime. And their mind is also at a good moment, their are both smart and dumb enough to be fun. A few years early they are too immature, a few years later they are into that "emancipated woman" crap. Assuming they're still single in their 30's.
Nothing weird about this chart, but it is interesting to see what partner age women want in different age groups, how it evolves over time.