The country has an area of 21,831 square miles and a population of 4.5 million. Approximately 85 percent of the population is Roman Catholic and 6 percent is Serbian Orthodox Christian. Groups that constitute less than 5 percent of the population include Muslims, Jews, and followers of other religions. Religious affiliation correlates closely with the country's ethnic makeup. The Serbian Orthodox, predominantly ethnic Serbs associated with the SPC, live primarily in cities and areas bordering Bosnia and Herzegovina, Serbia, and Montenegro. Most members of other minority religious groups reside in urban areas. Most immigrants are Roman Catholic ethnic Croats from Bosnia.