I guess you didn't notice the part said the liberal percentage was at 17% when the poll started in '92 and has gone up to 25% while the conservatives started at 36% and have not grown at all. The increase in liberals came from the moderates who started at 43% and are now only 34%. 

I'm sure there will always be about 34% of the country that remains conservative but they certainly are not winning anyone over to their side. 

You are right that liberals dominate colleges. That is simply because their is a positive correlation between higher education and liberal leanings. 
http://www.people-press.org/2015/04/07/a-deep-dive-into-party-affiliation/ 
In fact, this also shows that Millennials lean left 51% to right 35% and the generation that leans the most right is the Silent generation and that is only by 4 points. 

Not to mention that uneducated white males are the largest GOP demographic and all demographics beside white males lean left.