of Pakistanis are Muslim. Pakistan has the second largest number of Muslims in the world after Indonesia. The majority are Sunni (estimated at 85-90%), with an estimated 10-15% Shia. A PEW survey in 2012 found that 6% of Pakistani Muslims were Shia. There are a number of Islamic law schools called Madhab (schools of jurisprudence), which are called fiqh or 'Maktab-e-Fikr' in Urdu. Nearly all Pakistani Sunni Muslims belong to the Hanafi Islamic school of thought, while a small number belong to the Hanbali school. The majority of Pakistani Shia Muslims belong to the Twelver (Ithna Asharia) branch, with significant minority who adhere to Ismailism branch that is composed of Nizari (Aga Khanis), Mustaali, Dawoodi Bohra, Sulaymani, and others. Sufis and above mentioned Sunni and Shia sects are considered to be Muslims according to the Constitution of Pakistan. The mosque is an important religious as well as social institution in Pakistan. Many rituals and ceremonies are celebrated according to Islamic calendar. Sufi Islam to some extent syncretized with pre-Islamic influences, resulting in a religion with some traditions distinct from those of the Arab world. Two Sufis whose shrines receive much national attention are Ali Hajweri in Lahore (ca. 11th century) and Shahbaz Qalander in Sehwan, Sindh (ca. 12th century). Sufism, a mystical Islamic tradition, promoted by Fariduddin Ganjshakar in Pakpatan, has a long history and a large popular following in Pakistan. Popular Sufi culture is centered on Thursday night gatherings at shrines and annual festivals which feature Sufi music and dance. Contemporary Islamic fundamentalists criticize its popular character, which in their view, does not accurately reflect the teachings and practice of the Islamic prophet Muhammad and his companions. There have been terrorist attacks directed at Sufi shrines and festivals, 5 in 2010 that killed 64 people. Ahmadiyya According to the last Census in Pakistan, Ahmadi made up 0.22% of the population; however, the Ahmadiyya community boycotted the census. Independent groups generally estimate the population to be somewhere between two and five million Ahmadis. In media reports, four million is the most commonly cited figure. In 1974, the government of Pakistan amended the Constitution of Pakistan to define a Muslim according to Qu'ran 33:40, as a person who believes in finality of Muhammad under the Ordinance XX. According to Ordinance XX, Ahmadis cannot call themselves Muslim or "pose as Muslims" which is punishable by three years in prison. Ahmadis believe in