person, and just one-fourth of four and more persons. Average life expectancy in Serbia at birth is 76.1 years. During the 1990s, Serbia had the largest refugee population in Europe. Refugees and internally displaced persons (IDPs) in Serbia formed between 7% and 7.5% of its population at the time – about half a million refugees sought refuge in the country following the series of Yugoslav wars, mainly from Croatia (and to a lesser extent from Bosnia and Herzegovina) and the IDPs from Kosovo. Serbs with 5,988,150 are the largest ethnic group in Serbia, representing 83% of the total population (excluding Kosovo). Serbia is one of the European countries with the highest number of registered national minorities, while the province of Vojvodina is recognizable for its multi-ethnic and multi-cultural identity. With a population of 253,899, Hungarians are the largest ethnic minority in Serbia, concentrated predominantly in northern Vojvodina and representing 3.5% of the country's population (13% in Vojvodina). Romani population stands at 147,604 according to the 2011 census but unofficial estimates place their actual number between 400,000 and 500,000. Bosniaks with 145,278 are concentrated in Raška (Sandžak), in the southwest. Other minority groups include Croats, Slovaks, Albanians, Montenegrins, Romanians and Vlachs, Macedonians and Bulgarians. Chinese, estimated at 15,000, are the only significant non-European immigrant minority. The majority of the population, or 59.4%, reside in urban areas and some 16.1% in Belgrade alone. Belgrade is the only city with more than a million inhabitants and there are four more with over 100,000 inhabitants. Religion The Constitution of Serbia defines it as a secular state with guaranteed religious freedom. Orthodox Christians with 6,079,396 comprise 84.5% of country's population. The Serbian Orthodox Church is the largest and traditional church of the country, adherents of which are overwhelmingly Serbs. Other Orthodox Christian communities in Serbia include Montenegrins, Romanians, Vlachs, Macedonians and Bulgarians. In 2011, Roman Catholics numbered 356,957 in Serbia, or roughly 6% of the population, mostly in northern Vojvodina which is home to ethnic minority groups such as Hungarians, Croats, and Bunjevci, as well as to some Slovaks and Czechs. Protestantism accounts for about 1% of the country's population, chiefly Lutheranism among Slovaks in Vojvodina as well as Calvinism among Reformed Hungarians. Greek Catholic Church is adhered by around 25,000 citizens (0.37% of the population), mostly Rusyns in Vojvodina. Muslims, with 222,282 or 3% of the population, form the third largest religious group. Islam