However, Figure 5 also show's dramatic differences in United States income growth rates in the 1940s, and since 1980. Evidently, there can be quite long periods of unbalanced grow'th. In the 1940s, bottom end incomes grew' much more strongly than those at the top end and American income inequality lessened dramatically - but the last thirty years have been dominated by the opposite dynamic. Real income is expressed at 2011 US Dollars. Tax units are families (see source for details).