six censuses conducted in 1911, 1921, 1931, 1946, 1951 and 1956, prior to independence, but their population was estimated. By 1956, there were 65,277 Europeans, 5,450 Asiatics, and an estimated 2,100,000 black Africans. Zambia continues to have a small population of a historically mixed race group referred to as "Coloured" or Goffal, a group made up largely of people with black African and white British heritage (at times Indian heritage). Coloureds have not been recorded on the census since Zambia gained independence in 1964 and have not enjoyed the same rights as other groups (read: Goffal). In the 2010 population census, 99.2% were black Africans and 0.8% consisted of other racial groups. Zambia is one of the most highly urbanised countries in sub-Saharan Africa, with 44% of the population concentrated along the major transport corridors, while rural areas are sparsely populated. The fertility rate was 6.2 (6.1 in 1996, 5.9 in 2001–02). Largest towns The onset of industrial copper mining on the Copperbelt in the late 1920s triggered rapid urbanisation. Although urbanisation was overestimated during the colonial period, it was substantial. Mining townships on the Copperbelt soon dwarfed existing centres of population and continued to grow rapidly following Zambian independence. Economic decline in the Copperbelt from the 1970s to the 1990s has altered patterns of urban development, but the country's population remains concentrated around the railway and roads running south from the Copperbelt through Kapiri Mposhi, Lusaka, Choma and Livingstone. Ethnic groups The population includes approximately 73 ethnic groups, most of which are Bantu-speaking. Almost 90% of Zambians belong to the nine main ethnolinguistic groups: the Nyanja-Chewa, Bemba, Tonga, Tumbuka, Lunda, Luvale, Kaonde, Nkoya and Lozi. In the rural areas, ethnic groups are concentrated in particular geographic regions. Many groups are small and not well known. However, all the ethnic groups can be found in significant numbers in Lusaka and the Copperbelt. In addition to the linguistic dimension, tribal identities are relevant in Zambia. These tribal identities are often linked to family allegiance or to traditional authorities. The tribal identities are nested within the main language groups. Immigrants, mostly British or South African, as well as some white Zambian citizens of British descent, live mainly in Lusaka and in the Copperbelt in northern Zambia, where they are either employed in mines, financial and related activities or retired. There were 70,000 Europeans in Zambia in 1964, but many have since left