People have discussed why the grades have been going up and whether this is a bad thing.

I (Andrew Gelman, professor of statistics, http://www.stat.columbia.edu/~gelman/ ) have a slightly different take on all this. As a teacher who, like many others, assigns grades in an unregulated environment (that is, we have no standardized tests and no rules on how we should grade), all the incentives to toward giving only A’s.

So the real question is, why have grades been going up so slowly?