You should have broken this out more in the core ages of 15-35. There are not a lot of similarities between someone born in 1980 and 1989 when it comes to how they relate to Civ. One might have gotten the original, while the other certainly didn't start playing until well after 2 was out and possibly 3.
The best year to be born in is... 69.
Let's hear it for the (currently) 7 70+ year-olds, most of who knew most of the Civ leaders when they were actually alive!