Most of the nation's schools are operated by local authorities or by missions and are aided by the central government. A small number of schools are directly administered by the government. Primary education lasts for seven years and is compulsory. Secondary education lasts for five years. In 1995, 1,506,349 pupils were in 3,883 primary schools, with 38,528 teachers. At the secondary level, 199,154 students were enrolled in general education in 1994. The pupil-teacher ratio at the primary level was 47 to 1 in 1999. In the same year, 66% of primary-schoolage children were enrolled in school, while 21% of those eligible attended secondary school. Projected adult illiteracy rates for the year 2000 stand at 22.0% (males, 14.8%; females, 28.8%). As of 1999, public expenditure on education was estimated at 2.3% of GDP. The University of Zambia was established in 1965, and the Copperbelt University opened in 1986. Other institutions of higher learning include technical colleges and a two-year college of agriculture. All higher-level institutions had 15,343 pupils in 1990.