Islam is the second largest religion in Russia. It is popular in the Caucasus region and some republics in central Russia. In 2012, Muslims made up almost 7% of the population. However, this number does not include the Muslim-majority republics of Chechnya and Ingushetia. Between 1998 and 2007, the number of Muslims in Russia doubled from 5.9 million to 11.4 million. Most Muslims in Russia are Sunni. A little over 10% of the Muslim population is Shia. Sunni Sufism is a tradition in some areas, notably Chechnya and Dagestan.