ANN ARBOR, Mich. — At prestigious universities around the country, from flagship state colleges to the Ivy League, more and more students from upper-income families are edging out those from the middle class, according to university data. The change is fast becoming one of the biggest issues in higher education. More members of this year's freshman class at the University of Michigan have parents making at least $200,000 a year than have parents making less than the national median of about $53,000, according to a survey of Michigan students. At the most selective private universities across the country, more...