Scotland a territorial parish structure, with every community in Scotland having a local congregation. Scotland also has a significant Roman Catholic population, 19% professing that faith, particularly in Greater Glasgow and the north-west. After the Reformation, Roman Catholicism in Scotland continued in the Highlands and some western islands like Uist and Barra, and it was strengthened during the 19th century by immigration from Ireland. Other Christian denominations in Scotland include the Free Church of Scotland, and various other Presbyterian offshoots. Scotland's third largest church is the Scottish Episcopal Church. Islam is the largest non-Christian religion (estimated at around 75,000, which is
Religion in Scotland branches). During much of the 20th century and beyond, significant numbers of Catholics emigrated to Scotland from Italy, Lithuania, and Poland. However, the church has been affected by the general decline in churchgoing. Between 1994 and 2002 Roman Catholic attendance in Scotland declined 19%, to just over 200,000. By 2008, the Bishops' Conference of Scotland estimated that 184,283 attended mass regularly in that year: 3.6% of Scotland's population. According to the 2011 census, Catholics comprise 15.9% of the overall population. In 2011, Catholics outnumbered adherents of the Church of Scotland in just four of the council areas, including North Lanarkshire,