The notion that the middle class is shrinking is controversial because the economic boundaries that define the middle class vary. Households that earn between $25,000 and $75,000 represent approximately the middle half of the income distribution tables provided by the U.S. Census Bureau. Over the past two decades, the number of households in those brackets decreased by 3.9%, from 48.2% to 44.3%. During the same time period, the number of households with incomes below $25,000 decreased 3.5%, from 28.7% to 25.2%, while the number of households with incomes above $75,000 increased over 7%, from 23.2% to 30.4%.[44] A possible explanation for the increase in the higher earnings categories is that more households now have two wage earners.[45] However, a closer analysis reveals all of the 7% increase can be found in households who earn over $100,000.[44]