In the U.S., recent figures place the number of students with disabilities in college over 1.6 million, or over 11% of all students in higher education. The largest group are individuals with learning disabilities. See:
Henderson, C. (2001). College freshmen with disabilities: A biennial statistical profile. Washington, DC: American Council on Education.
and
Horn, L., & Nevill, S. (2006). Profile of undergraduates in U.S. postsecondary education institutions: 2003–04 with a special analysis of community college students (NCES 2006-184). Washington, DC: U.S. Department of Education.