The date range starts just prior to the .com bubble bust. It's not clear that you wouldn't see a similar result for a like period in 1986 (before the Oct 1987 market crash), although the .com era had more froth and a lot more capital gains income to skew the numbers. Also remember that a lot of people are still using up capital gains losses from the 2000 bust today, depressing current income.

Numbers like this often aren't adjusted for things like inflation because economists will want to do different analysis on raw data. For example, there *isn't* just one inflation rate - there are many different ways to measure it, and which you use matters.

For example the "core" inflation rate you usually see reported excludes energy prices, yet when last I looked the price of gas/oil really does matter to some people...