Business Week economist Michael Mandel has produced a terrific chart comparing college costs to the earnings of young college graduates (25- to 34-year-olds) from 1991 to 2008 (below).

While the lines track one another for most of the 1990s, they began to diverge by the late 1990s, and the gap has grown considerably over the past decade. Mandel finds that college costs in real terms are up by 23 percent since 2000, while real pay for young college grads has fallen by 11 percent.

Money quote:  "This can't go on. It's just not possible."

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