In 1997 36,896 students were enrolled in 72 primary schools, with 1,096 teachers and a student to teacher ratio of 34 to 1. Secondary schools had a total of 13,311 students in the same year. The pupil-teacher ratio at the primary level was 32 to 1 as of 1999. In the same year, 31% of primary-school-age children were enrolled in school. Education is compulsory for six years at the primary level followed by seven years of secondary education. Projected adult illiteracy rates for the year 2000 stand at 48.6% (males, 35%; females, 61.6%). In 1997, there were 161 students engaged in post-secondary education, 44% of which were female. As of 1990, public expenditure on education was estimated at3.5% of GDP.