In 2018 the literacy rate was 93.8%. The youth literacy rate was 98.1% in 2015. Education is provided by a well-organised school system of kindergartens, primary, lower secondary and upper secondary schools, numerous vocational colleges, and universities. The private sector of education is well developed and significantly contributes to the overall provision of education which the government would not be able to meet with public establishments. Education is compulsory up to and including age 14, with the government providing free education through to age 17. Thailand is the 3rd most popular study destination in Asean. The number of international degree students in Thailand increased by fully 979% between 1999 and 2012, from 1,882 to 20,309 students. The most of international students come from Asian neighbor countries from China, Myanmar, Cambodia and Vietnam. The number of higher education institutions in Thailand has grown strongly over the past decades from just a handful of universities in the 1970s to 156 officially. The two top-ranking universities in Thailand are Chulalongkorn University and Mahidol University. Thai universities research output still relatively low by international ranking comparison, Recent initiatives, such as the "National Research University" from 9 universities around the country and "Graduate research intensive university: VISTEC", designed to strengthen Thailand's national research universities, however, appear to be gaining traction. Thailand's research output, as measured by journal publications, increased by 20% between 2011 and 2016.