It is estimated that more than half of the world’s six billion people now live in cities, towns and other urban spaces. Current trends predict that this number will continue to rise with urban population  growth being significantly more pervasive and rapid in the developing world than that of the developed. According to the World Bank, over 90 percent of recent urbanization has occurred in developing countries, with urban areas gaining an estimated 70 million new residents each year. This trend is specially prevalent in  South Asia and Sub-Saharan Africa, the two poorest regions in the world, where the urban population is expected to double by 2030.