Nigeria is a large West African country, more than 900 000 km2 in area–nearly four times the size of the UK. Despite having a population of about 117 million people, 42% of whom live in cities, Nigeria has about half the population density of the UK. About a sixth of all Africans are Nigerian. The country has a diverse ethnic mix, with over 200 spoken languages, of which three (Yoruba, Hausa and Ibo) are spoken by about 60% of the population. The official language of government and educational instruction is English. There is a federal system of government and 36 states. Religious practice has a major role in Nigeria's culture; of the two main religions, Islam predominates in the northern part of the country and Christianity in the south. A large proportion of the population still embraces traditional religions exclusively, or interwoven with either Islam or Christianity.