Demographics of Iraq
97% of Iraqis follow Islam: 61% Shia and 34% Sunni. 1% of these describe themselves as "Just a Muslim". According to the CIA Factbook, Shias make up 60% of population, while Sunnis 35%. Christianity accounts for 5%, and the rest practice Mandaeism, Yazidism and other religions.
Islam
A comprehensive 2015 demographic study of 232 countries and territories reported that 24% of the global population, or 1.8 billion people, are Muslims. Of those, it is estimated that over 75–90% are Sunni and 10–20% are Shia with a small minority belonging to other sects. Approximately 57 countries are Muslim-majority, and Arabs account for around 20% of all Muslims worldwide. The number of Muslims worldwide increased from 200 million in 1900 to 551 million in 1970, and tripled to 1.8 billion by 2015.