Education is not compulsory but is free through the first eight years. There are government schools as well as private schools operated by individual groups or by missions under government supervision. In 1990, public expenditure on education was 4.6% of GDP. In the mid-1990s there were 4,644 teachers and 145,630 pupils in 693 primary schools. Secondary schools had 3,631 teachers and 66,890 students. Of these, 6,653 students were enrolled in technical and vocational schools. The pupil-teacher ratio at the primary level was 23 to 1 in 1999. In the same year, 99% of primary-school-age children were enrolled in school. The University of the South Pacific, which opened in Suva in 1968, had more than 3,600 students in the mid-1990s. Its students are drawn from several Pacific island states. All third-level institutions and universities had approximately 8,000 students and a faculty staff nearing 300 personnel. Adult illiteracy rates for the year 2000 were estimated at 7.1% (males, 5.0%; females, 9.1%).