Every year researchers at U.C.L.A. do a survey of incoming college freshmen. These surveys, conducted over four decades now, show how the life cycle has changed over the past couple generations.
This first thing you see from this and similar data sets is that high school has gotten a bit easier. In 1966, only about 19 percent of high school students graduated with an A or A- average. By 2013, 53 percent of students graduated with that average.