with significant improvement since 2006. In mathematics, however, the top scoring 10% were estimated to lag three years behind the top scoring students in Shanghai. Upper secondary school (Videregående skole, Grades VG1-VG3, ages 16–19) Secondary education in Norway is primarily based on public schools: In 2007, 93% of upper secondary school students attended public schools. Until 2005, Norwegian law held private secondary schools to be illegal unless they offered a "religious or pedagogic alternative", so the only private schools in existence were religious (Christian), Steiner/Waldorf, Montessori schools, and . The first "standard" private upper secondary schools opened in the fall of 2005. Videregående is the equivalent to a high school. As of 2017, graduation from videregående skole was at 73%. Prior to 1994, there were three branches of upper secondary schooling: "General" (language, history, etc.), "mercantile" (accounting, etc.), and "vocational" (electronics, carpentry, etc.) studies. The high school reform of 1994 ("Reform 94") merged these branches into a single system. Among the goals of the reform was that everybody should have a certain amount of "general studies" large enough to make them eligible for higher education later, meaning more theory in vocational studies, and it should be possible to cross over from one education path to another without losing too much credit. In the old system, two years of carpentry would be wasted if you wanted to switch to general studies, but in the new system you could keep credit for at least half of it. Since the introduction of the reform Kunnskapsløftet ("the knowledge promise" or "the lifting of knowledge," the word løfte having two meanings) in the fall of 2006, a student can apply for a general studies (studieforberedelse) or a vocational studies (yrkesfag) path. Inside these main paths, there are many sub-paths to follow. An upper secondary school usually offers general and vocational curriculum. Vocational studies usually follow a typical structure named the "2+2 model": After two years of school training (with workshops and short internship in industry), the student goes in apprenticeship for two years in an enterprise or a public institution. The apprenticeship is divided into one year of training and one year of effective work. Some vocational curriculum are nonetheless entirely school-based, and other include three years of apprenticeship instead of two. The new reform makes the incorporation of IT into the schooling mandatory, and many counties (responsible for the public high schools) offer laptops