NPR's Planet Money has a feature on household inequality in the United States shown in graphics. The graphic above on household income over the last 40 years is particularly striking: After adjusting to inflation, you can see that the lowest incomes have barely moved. In fact, they went down.
By contrast, the top layers of the population skyrocket despite any economical crisis. Basically, the upper percentiles keep absorbing more and more money while the lower ones, the largest parts of the population, fight for the crumbles while carrying the weight of productivity.