Compulsory education was established in Norway by the Primary School Act of 1827. Changes made since the 1960s have reduced regional disparities and increased access for all social groups to the educational system. Education is free and compulsory in all municipalities for children from age 7 to age 15. Norway has almost no illiteracy. For their primary education, children attend a six-year lower school and a three-year upper school. Three years of secondary school is then available.