The Cushitic languages, which are less closely related than the Semitic, are found mainly in the south of the country. The most important tongue in this group is Afan Oromo. It is used in a wide stretch of country, including Welega and parts of Ilubabor in the west, Wollo in the north, Shewa and Arsi in the centre, Bale and Sidamo in the south, and Harerge in the east. Other Cushitic language in the area comprise Somalinya, which is spoken by the Somali in the Ogaden to the east, as well as in the neighboring Somali Republic and part of Djibouti, and the Sidaminya language, used in part of the Sidama region. Cushitic languages, however, are also used in the north of the country, namely Afarinya, spoken by the Afar of eastern Wollo and the northern half of the Djibouti Republic; Saho, in parts of Tigray; and Agawinya, in small pockets in different parts of western Ethiopia. The Omotic group of languages, which comprise considerably fewer speakers than either the Semitic or the Cushitic, are spoken the south-west of the country, mainly in Gamo Gofa. They have been given the name in recent years because they are spoken in the general area of the Omo River. The Nilo-Saharan languages, largely peripheral to Ethiopian civilization, are spoken in a wide arc of the country towards the Sudan frontier. They include, from north to south, Gumuz in Gondar and Gojjam, Berta in Welega, and Anuak in Ilubabor  Various religions are adhered to in Ethiopia. Most Christians live in the highlands, whereas Muslims mainly inhabit the lowlands. Adherents of traditional faiths are primarily concentrated in the southern regions. According to the Ethiopian Central Statistical Agency (2007 census), the national religious composition is Ethiopian Orthodox 43.5%, Protestantism 18.6%, Roman Catholicism 0.7%, Islam 33.9%, traditional 2.6%, and others 0.6%. Source: Central Statistical Agency (CSA)  According to , the total population was in , compared to 18,434,000 in 1950. The proportion of children below the age of 15 in 2010 was 41.5%, 55.8% was between 15 and 65 years of age, while 3.3% was 65 years or older. The average age was 25.1.