“Since the 1960s, the national mean G.P.A. at the institutions from which he’s collected grades has risen by about 0.1 each decade – other than in the 1970s, when G.P.A.s stagnated or fell slightly. In the 1950s, according to Rojstaczer’s data, the mean G.P.A. at U.S. colleges and universities was 2.52. By 2006-07, it was 3.11.”