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.
Sectarianism
Pakistan, one of the largest Muslim countries the world, has seen serious Shia-Sunni sectarian violence. Almost 80 - 85 
of Pakistan's Muslim population is Sunni, and another 10 - 20% are Shia. However, this Shia minority forms the second largest Shia population of any country, larger than the Shia majority in Iraq.