The former Socialist Republic of Slovenia, a member of the Yugoslav federation, became an independent nation in 1991. Though estimates vary, the 1991 census indicated that the largest denominational group is the Roman Catholic Church, at about 72% of the population. There is also a Slovenian Old Catholic Church and some Eastern Orthodox that make up about 2% of the population. Although Calvinism played an important role during the Reformation, the only well-established Protestant group is the Evangelical Lutheran Church of Slovenia, which accounts for 1% of the population. Muslims make up another 1.5%; atheists form 4.3%; 0.2% are agnostic, and 0.01% are Jewish.