The Gender Parity Index in Islamabad is 0.93 compared to the 0.95 national average. There are 178 boys only institutes, 175 girls only, and 551 mixed institutes in Islamabad. Total enrolment of students in all categories is 267,992; 138,272 for boys and 129,720 for girls. There are 16 recognised universities in Islamabad with a total enrolment of 372,974 students and 30,144 teachers. Most of the top ranked universities; National University of Sciences and Technology, COMSATS Institute of Information Technology and Pakistan Institute of Engineering & Applied Sciences, also have their headquarters in the capital. The world's second largest general university by enrolment, Allama Iqbal Open University is located in Islamabad for distance education. Other universities include Air University, Bahria University, Center for Advanced Studies in Engineering, Federal Urdu University of Arts, Science and Technology, Hamdard University, National University of Computer and Emerging Sciences, Capital University of Science & Technology, National Defence University, Shifa Tameer-e-Millat University, National University of Modern Languages, Iqra University, International Islamic University, Virtual University of Pakistan, Muhammad Ali Jinnah University, The University of Lahore, Abasyn University, and The Millennium University College.