" On the first page of a fifty-six-page report, I find this sentence: “The average reading score for 17-year-olds was not significantly different from that in 1971.” On the same page, a little further below, I find: “The average mathematics score for 17-year-olds was not significantly different from that in 1973.” There are plenty of ways you can slice and dice these numbers with statistics, but the bottom line is that an “eyeball test” shows very little in terms of net gains on the tests, and that’s speaking over decades. "

― Tyler Cowen , The Great Stagnation: How America Ate All The Low-Hanging Fruit of Modern History, Got Sick, and Will (Eventually) Feel Better