Men's vs. Women's "Sexual Peaks:" Where did these numbers come from?

This evening I heard it mentioned for the zillionth time that men reach their sexual peak at 19 or so and women reach it in their mid-thirties.

I resisted the urge to say “cite?”

Does anybody know where these numbers came from? Was it Kinsey? Has there been any recent research on the matter?

And what is a “sexual peak” anyway?

Thanks in advance.

A five-second Google search finds this article says Kinsey.