"In his analysis of the numbers for higher education, Hinrichs found that the index fell sharply in the direction of desegregation as the civil rights movement and court rulings led predominantly white colleges to recruit black students. In 1968 the index was 63.9 percent, and by 1972, the index had dropped to 52.5 percent. But since then, movement has been modest. and the figure had dropped only to 48.0 percent by 2009."
Food for thought, and data to be chewed on.