The proportion of full-time tenured and tenure-track faculty in the United States has declined since the late 1990s and higher-education institutions are relying more on non-tenured 'contingent' faculty members, according to a report by the American Federation of Teachers. The higher-education instructional workforce grew in the past decade along with rising enrolments, the report finds. But colleges and universities have increasingly turned to part-time and full-time non-tenured faculty. From 1997 to 2007, full-time tenured and tenure-track faculty members declined from about a third of the instructional staff to slightly more than a quarter. A similar change was found in all sectors of higher education.