Turkey is a secular state with no official state religion; the Turkish Constitution provides for freedom of religion and conscience. A 2016 survey by Ipsos, interviewing 17,180 adults across 22 countries, found that Islam was the dominant religion in Turkey, adhered to by 82% of the total population; religiously unaffiliated people comprised 13% of the population, while 2% were Christians. According to a religiosity poll conducted in Turkey in 2019 by OPTİMAR, 89.5% of the population identifies as Muslims, 4.5% believed in God but did not belong to any organized religion, 2.7% were agnostics, 1.7% were atheists, and 1.7% did not answer. Another poll conducted by Gezici Araştırma in 2020 interviewed 1,062 people in 12 provinces and found that 28.5% of the Generation Z in Turkey identify as irreligious. The ''CIA World Factbook'' reports that Islam is the religion of 99.8% of the population, with Sunni Muslims as the largest sect, while 0.2% are Christians and Jews. However, there are no official governmental statistics specifying the religious beliefs of the Turkish people, nor is religious data recorded in the country's census. Academics suggest the Alevi population may be from 15 to 20 million, while the Alevi-Bektaşi Federation states that there are around 25 million. According to Aksiyon magazine, the number of Twelver Shias (excluding Alevis) is three million (4.2%).