Presidents at 23 private U.S. higher education institutions each took home more than $1 million in compensation between 2007 and 2008, according to a report published Monday in the Chronicle of Higher Education. At the top of the list is Shirley Ann Jackson, president of Rensselaer Polytechnic Institute. She made almost $1.6 million. The median salary at the 419 nonprofit colleges and universities examined in the report was $358,746, up 6.5 percent from the previous year. Chronicle editors, who have been conducting the annual report since 1993, say it has shown continual increases year after year. Next year’s report, which will look at 2008-2009, is expected to reveal the impact of the economic crisis.