<Li> W. African CFA franc (XOF) </Li> <Tr> <Th> Largest cities </Th> <Td> Lagos, Nigeria Abidjan, Ivory Coast Accra, Ghana Abuja, Nigeria Kumasi, Ghana Port Harcourt, Nigeria </Td> </Tr> <P> West Africa, also called Western Africa and the West of Africa, is the westernmost subregion of Africa . West Africa has been defined as including 18 countries: Benin, Burkina Faso, the island nation of Cape Verde, Gambia, Ghana, Guinea, Guinea - Bissau, Ivory Coast, Liberia, Mali, Mauritania, Niger, Nigeria, the island of Saint Helena, Senegal, Sierra Leone, São Tomé and Príncipe and Togo . The population of West Africa is estimated at about 362 million people as of 2016...</P> <Table> <Tr> <Th> Region </Th> <Th> Country </Th> </Tr> <Tr> <Td> Western Africa </Td> </Tr> <Tr> <Td> Benin </Td> </Tr> <Tr> <Td> Burkina Faso </Td> </Tr> <Tr> <Td> Cape Verde </Td> </Tr> <Tr> <Td> Ivory Coast </Td> </Tr> <Tr> <Td> Gambia </Td> </Tr> <Tr> <Td> Ghana </Td> </Tr> <Tr> <Td> Guinea </Td> </Tr> <Tr> <Td> Guinea - Bissau </Td> </Tr> <Tr> <Td> Liberia </Td> </Tr> <Tr> <Td> Mali </Td> </Tr> <Tr> <Td> Mauritania </Td> </Tr> <Tr> <Td> Niger </Td> </Tr> <Tr> <Td> Nigeria </Td> </Tr> <Tr> <Td> Saint Helena, Ascension and Tristan da Cunha <P> (United Kingdom) </P> </Td> </Tr> <Tr> <Td> Senegal </Td> </Tr> <Tr> <Td> Sierra Leone </Td> </Tr> <Tr> <Td> Togo </Td> </Tr> </Table>

How many countries are there in west africa