Public education at the primary level is compulsory for eight years, between the ages of 7 and 15. In 1997, there were 260,917 students enrolled in 1,086 primary schools, with 13,394 teachers. The student-to-teacher ratio stood at 19 to 1. There are also many secondary-level schools. In 1997, 83,746 students were enrolled in secondary schools, with 5,136 teachers. As of 1999, approximately 95% of primary-school-age children were enrolled in school. At the postsecondary level, there are two universities: the Bitola University, which was founded in 1979, and the University of Skopje, founded in 1949. The language of instruction is Macedonian, and there are faculties of law, engineering, medicine, arts, science, physical education, architecture, and agriculture. In 1997, institutions of higher learning had a combined enrollment of 30,754 students; teaching staff totaled 2,462. In the latter half of the 1990s, expenditure on education accounted for 5.6% of GNP and approximately 20.0% of public expenditures.