Slovenia's education ranks as the 12th best in the world and 4th best in the European Union, being significantly higher than the OECD average, according to the Programme for International Student Assessment. Among people age 25 to 64, 12% have attended higher education, while on average Slovenes have 9.6 years of formal education. According to an OECD report, 83% of adults ages 25–64 have earned the equivalent of a high school degree, well above the OECD average of 74%; among 25- to 34-year-olds, the rate is 93%. According to the 1991 census there is 99.6% literacy in Slovenia. Lifelong learning is also increasing.