offering the Primary Years Programme, Middle Years Programme and Diploma Programme. Shahid Mahdavi School is an IB world school in Tehran offering the Primary Years Programme and Middle Years Programme. Tehran International School is an IB world school in Tehran offering the Diploma Programme. Statistics Iran produces the third highest number of engineers in the world. Around 70% of engineering graduates are women. As of 2016 Iran has the 5th highest number of STEM graduates worldwide with 335,000 annual graduates. In 2010, 64% of the country's population was under the age of 30. There are approximately 92,500 public educational institutions at all levels, with a total enrollment of approximately 17,488,000 students. According to 2008 estimates, 89.3% of males and 80.7% of females over the age of 15 are literate; thus 85% of the population is literate. Virtually all children of the relevant age group enrolled into primary schools in 2008 while enrollment into secondary schools increased from 66% in 1995 to 80% in 2008. As a result, youth literacy rates increased from 86% to 94% over the same period, rising significantly for girls. A literacy corps was established in 1963 to send educated conscripts to villages. During its first 10 years, the corps helped 2.2 million urban children and 600,000 adults become literate. This corps was replaced with the Literacy Movement Organization after the Islamic Revolution. In 1997, there were 9,238,393 pupils enrolled in 63,101 primary schools, with 298,755 teachers. The student-to-teacher ratio stood at 31 to 1. In that same year, secondary schools had 8,776,792 students and 280,309 teachers. The pupil-teacher ratio at the primary level was 26 to 1 in 1999. In the same year, 83% of primary-school-age children were enrolled in school. As of 1999, public expenditure on education was estimated at 4.6% of GDP (not budget). In 2007, the majority of students (60%) enrolled in Iranian universities were women. According to UNESCO world survey, Iran has the highest female to male ratio at primary level of enrollment in the world among sovereign nations, with a girl to boy ratio of 1.22 : 1.00. Each year, 20% of government spending and 5% of GDP goes to education, a higher rate than most other developing countries. 50% of education spending is devoted to secondary education and 21% of the annual state education budget is devoted to the provision of tertiary education. See also International Rankings of Iran in