As income inequality has increased in the United States over the last decade, so too has the gap between rich and poor colleges and universities.

Between 1999 and 2009, private research universities that enroll about 1.1 million students increased their education-related spending per student by about $7,500, to almost $36,000. But in that same period, education-related spending stayed nearly flat, at slightly more than $10,000 per student, at the public community colleges that enroll 6.7 million students, according to a report, “Trends in College Spending,” being released Wednesday.

“The growing gap between the haves and the have-nots has become much more exaggerated over the last 10 years,” said Jane Wellman, executive director of the Delta Project on Postsecondary Education Costs, Productivity and Accountability, the Washington, research group issuing the report.

While tuition has risen at public and private institutions alike, the inequality between the two sectors has grown, as the public colleges’ increased tuition revenues have not been nearly enough to make up for their loss of state and local appropriations.