Currently, one-third of developing-world urban people live in slums. UN-HABITAT estimates that in 2005, more than half of the world’s slum population lived in Asia, followed by sub-Saharan Africa, Latin America, and the Caribbean. In Asia, slum prevalence varies from a high of 43 percent in Southern Asia to a low of 24 percent in Western Asia, while in Latin America and the Caribbean, 27 percent of urban populations lived in slums in 2005. In urban and suburban areas, the lack of residential and communication infrastructure are a major contributing factor to slums and illegal habitats. A majority of the poor lives in slum and squatter settlements because formal housing options are unavailable.