In 2013, Gallup published a list of countries with median annual household income, based on a self-reported survey of approximately 2000 adults from each country.[1] Using median, rather than mean income, results in a much more accurate picture of the typical income of the middle class since the data will not be skewed by gains and abnormalities in the extreme ends. The figures are in international dollars using purchasing power parity and are based on responses from 2006 to 2012 inflation adjusted to 2010 levels.