“In the 1950s, less than 30% of the world’s population lived in cities. Currently, that proportion has risen to 50% and, by 2030, the UN projects that some 4.9 billion people will be urban dwellers. By 2015, the UN estimates that there will be 22 mega-cities—those with populations of 10 million or more—with 17 located in developing economies. By 2050, the world’s urban population will have increased by some 72%”