The G20 economies account for two-thirds of the world population.
 The United Nations and the US Census Bureau both give different estimates  according to the UN, the world population reached seven billion in late 2011, while the USCB asserted that this occurred in March 2012
 From 2000 to 2005, the UN consistently revised these projections downward, until the 2006 revision, issued on 14 March 2007, revised the 2050 mid-range estimate upwards by 273 million

