Income data indicate that the middle class, including the upper middle class, have seen far slower income growth than the top 1% since 1980. While its income increased as fast as that of the rich in the years following World War II, it has since experienced far slower income gains than the top. According to economist Janet Yellen "the growth real income was heavily concentrated at the very tip of the top, that is, the top 1 percent". Between 1979 and 2005, the mean after-tax income of the top 1% increased by an inflation adjusted 176% versus 69% for the top 20% overall. The fourth quintile saw its mean net income increase by 29%, the middle income quintile by 21%, the second quintile by 17% and the bottom quintile by 6%, respectively.