18-24 in 2016 is very different than 18-29 in 2015. Those 2015 23-29 year olds are far, far more liberal than the 2015 17-22 year olds. 1992 serves as a breaking point between a more liberal and a more centrist (or, really, more evenly polarized) generation.
Do you have a source for those claims?
I doubt it. I have a source though:
http://www.cnn.com/election/2014/results/race/house#exit-polls18-24: 54% Democrat 44% Republican 2% Other/NA
25-29: 54% Democrat 43% Republican 3% Other/NA
Not really much of a statistical difference.