Because "income" does not equal "all of the economic gains of a country." Lots of other things happened in the period in that graph which kept median incomes l

Because "income" does not equal "all of the economic gains of a country." Lots of other things happened in the period in that graph which kept median incomes lower despite economic improvements taking place. Like: 1. The offering of health insurance as a tax-free employment benefit. 2. An increase in divorce rates (households all over cut in half but the median household income didn't drop; there must have been an economic gain distributed to not-rich people for this to happen). Also, this graph doesn’t say anything about what happened to the size of each of these groups. Pretty sure the biggest trend in America has been the middle class splitting in half between people making more money (and thus becoming part of the "small few") and people making less (which worsens income inequality even though more people are now "rich"). So yeah, there's a lot missing from these graphs.