From the summary:
The real incomes of about two-thirds of households in 25 advanced economies were flat or fell between 2005 and 2014. Without action, this phenomenon could have corrosive economic and social consequences….
…..These findings provide a new perspective on the growing debate in advanced economies about income inequality, which until now has largely focused on income and wealth gains going disproportionately to top earners. Our analysis details the sharp increase in the proportion of households in income groups that are simply not advancing—a phenomenon affecting people across the income distribution. And the hardest hit are young, less-educated workers, raising the spectre of a generation growing up poorer than their parents…..