Nothing to add, other than I like how economists make stuff up like this.

I would hypothesize that the study time/booze consumption ratio amongst college students has fallen sharply over time. If a student spends 20 hours out of class per week on average studying, preparing papers, etc., and drinks on average the equivalent of 15 cans of beer per week, the ratio would be 1.33 (20 divided by 15). My guess is over the years study time has fallen fairly sharply, while booze consumption has increased. If the average ratio nationally in 1970 was 1.33, I would not be surprised that today it is closer to being less than one-half of that, say .50 (10 hours of studying, 20 cans of beer). (Center for College Affordability and Productivity: The Study Time-Booze Consumption Ratio)

HT: Club for Growth