Over the past five decades, the number of hours that the average college student studies each week has been steadily dropping. According to time-use surveys analyzed by professors Philip Babcock, at the University of California Santa Barbara, and Mindy Marks, at the University of California Riverside, the average student at a four-year college in 1961 studied about 24 hours a week. Today’s average student hits the books for just 14 hours.
The decline, Babcock and Marks found, infects students of all demographics. No matter the student’s major, gender, or race, no matter the size of the school or the quality of the SAT scores of the people enrolled there, the results are the same: Students of all ability levels are studying less.
via The Boston Globe.

Good point. The quantitative measure of the process (number of hours of study) does not necessarily account for the qualitative result of the process (learning).
the real question is are they learning less?