A team of Wayne State University researchers provided an analysis for the Brookings Institution in Washington that shows a faster decline in middle-income neighborhoods than middle-income families. \"Families earning between 80 percent and 120 percent of their metropolitan-area median incomes - what many would consider to be the \'middle class\' - shrank from 28 percent of the total in 1970 to less than 22 percent by 2000,\" according to the analysis, by Jason C. Booza, Jackie Cutsinger and George Galster of Wayne State University. The analysis attributed the shrinking number of middle-income communities to, among other factors, gentrification of more marginal neighborhoods and a bunching of high-income families in more homogenous surroundings.