INSIDE HIGHER ED. FEBRUARY 26, 2013. The National Student Clearinghouse Research Center today released a state-by-state rundown of graduation data, which is based on a broad sample representing about 97 percent of students who attend public and private nonprofit institutions. The report is a companion to a national completion data study the group released last fall. Both are based on students who first enrolled in 2006 at the 3,300 colleges and universities that submit data to the clearinghouse, which is a nonprofit that collects enrollment data and conducts degree verifications.