Israel has a school life expectancy of 15.5 years and a literacy rate of 97.1% according to the United Nations. The State Education Law, passed in 1953, established five types of schools: state secular, state religious, ultra orthodox, communal settlement schools, and Arab schools. The public secular is the largest school group, and is attended by the majority of Jewish and non-Arab pupils in Israel. Most Arabs send their children to schools where Arabic is the language of instruction. Education is compulsory in Israel for children between the ages of three and eighteen. Schooling is divided into three tiers – primary school (grades 1–6), middle school (grades 7–9), and high school (grades 10–12) – culminating with Bagrut matriculation exams. Proficiency in core subjects such as mathematics, the Hebrew language, Hebrew and general literature, the English language, history, Biblical scripture and civics is necessary to receive a Bagrut certificate. In Arab, Christian and Druze schools, the exam on Biblical studies is replaced by an exam on Muslim, Christian or Druze heritage. Christian Arabs are one of the most educated groups in Israel. Maariv have describe the Christian Arabs sectors as "the most successful in education system", since Christian Arabs fared the best in terms of education in comparison to any other group receiving an education in Israel. Israeli children from Russian-speaking families have a higher bagrut pass rate at high-school level. Although amongst immigrant children born in the FSU, the bagrut pass rate is highest amongst those families from Western FSU states of Russia, Ukraine, Belarus and Moldova (at 62.6%), and lower amongst those from Central Asian and Caucasian FSU states. In 2003, over half of all Israeli twelfth graders earned a matriculation certificate.