Iran is a regional and middle power, with a geopolitically strategic location in the Asian continent. It is a founding member of the United Nations, the ECO, the OIC, and the OPEC. It has large reserves of fossil fuels—including the world's second-largest natural gas supply and the fourth-largest proven oil reserves. The country's rich cultural legacy is reflected in part by its 22 UNESCO World Heritage Sites. Historically a multinational state, Iran remains a pluralistic society comprising numerous ethnic, linguistic, and religious groups, the largest being Persians, Azeris, Kurds, Mazandaranis and Lurs. Despite the Iranian government census claiming Iran to be 99.5% Muslim only 32.5% of Iranians identify with Shia Islam according to an independent online survey in 2020 by GAMAAN institution. Shifting religious demographics within the nation are seen as a result of growing secularism and Persian nationalism.