Though there are no exact figures on the Muslim sects, according to a 2006 survey, 82% were identified as Sunni Hanafi, 9.1% Sunni Shafi'i, and 5.7% were Alevi.[citation needed] Though academics suggest the Alevi population may be from 15 to 20 million.[140][141] Alevi community is sometimes classified within Twelver Shi'a Islam.[citation needed] According to Aksiyon magazine, the number of Shiite Twelvers (excluding Alevis) is 3 million (4.2%), and they live in Istanbul, Idr, Kars, Ankara, zmir, Manisa, Çorum, Mula, Ar and Aydn.[142] There are also some Sufi practitioners.[143] The highest Islamic religious authority is the Presidency of Religious Affairs (Turkish: Diyanet leri Bakanl), it interprets the Hanafi school of law, and is responsible for regulating the operation of the country's 80,000 registered mosques and employing local and provincial imams.[144] The role of religion has been controversial debate over the years since the formation of Islamist parties.[145] Turkey was founded upon a strict secular constitution which forbids the influence of any religion, including Islam. There are sensitive issues, such as the fact that the wearing of the Hijab is banned in universities and public or government buildings as some view it as a symbol of Islam – though there have been efforts to lift the ban.[146][147][148][149] The vast majority of the present-day Turkish people are Muslim and the most popular sect is the Hanafite school of Sunni Islam, which was officially espoused by the Ottoman Empire; according to the KONDA Research and Consultancy survey carried out throughout Turkey on 2007:[13] 52.8% defined themselves as "a religious person who strives to fulfill religious obligations" (religious); 34.3 % defined themselves as "a believer who does not fulfill religious obligations" (believer); 9.7% defined themselves as "a fully devout person fulfilling all religious obligations" (fully devout); 2.3% defined themselves as "someone who does not believe in religious obligations" (non-believer/agnostic); and 0.9% defined themselves as "someone with no religious conviction" (atheist).
The Sultan Ahmed Mosque in Istanbul.