In 1992, the 400th richest person in America made $24 million.

In 2007, the 400th richest person in America made $138 million (or $87 million, inflation-adjusted).

Now, that almost certainly wasn't the same guy. There's a lot of churn at the top of the money pyramid. In all of the 1990s, only 25% of the Fortunate 400 made more than one appearance. But the overall message is the same. The rich keep get much richer.