National data collected by the U.S. Department of Education finds that "private school students are more likely to be in racially mixed classes than are public school students." An empirical study of Milwaukee's school choice program by Howard Fuller of Marquette University found that "adding religious schools led to substantially more integration in parental school choice systems than in Milwaukee public schools...half of (public school) students attended racially isolated schools...compared to just 31.1% of students at religious choice schools. The result was more integration, achieved voluntarily." In Cleveland, an empirical study found that nearly 20% of voucher students attended schools that were racially representative of the city as a whole, whereas only 5% of Cleveland public school students attended such schools. In Washington, D.C., an empirical study found that 85% of public school students attend racially homogeneous schools, compared to 47% of students in private schools that participated in the city's parental school choice program.