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 keeping getting richer.

According to the IRS, which recently released 2009 data from the 400 richest individual income tax returns, the real runaway growth in wealth has come from capital gains. In the last years of the bubble, the "Fortunate 400" made nearly half their income from capital gains (a.k.a.: profit from the rising value of an investment, such as stocks or property) and less than 10% of their income from old-fashioned wages.

The average income of a top-400 earner grew by 650% between 1992 and 2007 to a whopping $344 million. Over that time, the average salary barely doubled. But the average capital gains haul increased by 1,200%. How do the richest get richer? Not from their wages. From their investments.

Here's a look at the average salary and average capital gains income of a top-400 earner since 1992. Y-axis is labeled in thousands of dollars and all-time highs are noted in the graph.