Princeton - apparently due to pressure from parents - is on the verge of losing its nerve in the battle against grade inflation (link). It is the most prestigious college to have instituted an A-grade quota. By contrast, 62 percent of all grades given at Yale are As and at Harvard, the most common grade given is A. At Stanford, 93 percent of grades were As or Bs, and that was 20 years ago(!) and then it decided to hide its grade distribution.
Presented without comment the nation-wide grade trends: