Average age of wife’s lover.

I was wondering the other day about the average age for my wife’s lovers. My wife is about 50 and all her partners are younger than her. She recently slept with a guy half her age, but regularly hooks up with guy 10 to 15 years younger than her. She never has any problems picking up younger guys and she says the sex is generally better as they have a lot more stamina!

Is this just my wife or do other wives tend to go for younger guys?