A study carried out in 2008 by the Angolan Instituto Nacional de Estatística found that in rural areas roughly 58% must be classified as "poor" according to UN norms but in the urban areas only 19%, and an overall rate of 37%. In cities, a majority of families, well beyond those officially classified as poor, must adopt a variety of survival strategies. In urban areas social inequality is most evident and it is extreme in Luanda. In the Human Development Index Angola constantly ranks in the bottom group.