Education at the elementary level is free and compulsory for children between the ages of 7 and 15 years. Secondary education lasts from two to five years and is of three kinds: grammar; technical and specialized; and mixed-curriculum. In 1997, there were 203,933 students enrolled in 1,094 primary schools, with 10,762 teachers. Student-to-teacher ratio stood at 19 to 1. Secondary schools enrolled 416,829 students and employed 31,070 teachers the same year. As of 1999, 72% of primary-school-age children were enrolled in school, while 79% of those eligible attended secondary school. In 1995, public expenditure on education was estimated at 5.1% of GDP.
For the year 2000, the rate of adult illiteracy was estimated at1.7% (males, 0.6%; females, 2.7%). In higher education, there are four universities and three polytechnic institutes: University of Osijek (founded in 1975); University of Rijeka (founded in 1973); University of Split (founded in 1974); and University of Zagreb (founded in 1669). In 1997, Croatia's universities, technical schools, and arts academies had 6,038 teachers and enrolled a combined total of 85,752 students.