one outside the capital of Beijing after the Chinese Academy of Social Sciences (CASS). By the end of 2019, the city also had 929 secondary schools, 698 primary schools, and 31 special schools. In Shanghai, the nine years of compulsory education—including five years of primary education and four years of junior secondary education—are free, with a gross enrollment ratio of over 99.9%. The city's compulsory education system is among the best in the world: in 2009 and 2012, 15-year-old students from Shanghai ranked first in every subject (math, reading, and science) in the Program for International Student Assessment, a worldwide study of academic performance conducted by the OECD. The consecutive three-year senior secondary education is priced and uses the Senior High School Entrance Examination (Zhongkao) as a selection process, with a gross enrollment ratio of 98%. Among all senior high schools, the four with the best teaching quality—Shanghai High School, No. 2 High School Attached to East China Normal University, High School Affiliated to Fudan University, and High School Affiliated to Shanghai Jiao Tong University—are termed "The Four Schools" () of Shanghai. , the city's National College Entrance Examination (Gaokao) is structured under the "3+3" system, in which all general senior high school students study three compulsory subjects (Chinese, English, and math) and three subjects chosen from six options (physics, chemistry, biology, history, geography, and politics). Transport Public Shanghai has an extensive public transportation system comprising metros, buses, ferries, and taxis, all of which can be accessed using a Shanghai Public Transport Card. Shanghai's rapid transit system, the Shanghai Metro, incorporates both subway and light metro lines and extends to every core urban district as well as neighboring suburban districts. , there are 19 metro lines (excluding the Shanghai maglev train and Jinshan Railway), 515 stations, and of lines in operation, making it the longest network in the world. On 8 March 2019, it set the city's daily metro ridership record with 13.3 million. The average fare ranges from () to (), depending on the travel distance. Opened in 2004, the Shanghai maglev train is the first and the fastest commercial high-speed maglev in the world, with a maximum operation speed of . The train can complete the journey between Longyang Road Station and Pudong International Airport in 7 minutes 20 seconds, comparing to 32 minutes by Metro Line 2 and 30 minutes by car. A one-way ticket costs (),