Wood Mackenzie takes population data - both historical and forecast - from the United Nations. The United Nations publish population prospects every two years, and this data was last published in July 2015. Based on proprietary analysis, Wood Mackenzie made changes to forecast of Afghanistan, Albania, Germany, Iraq, Serbia, Syria, and China. For the US, forecast is produced using Wood Mackenzie's proprietary state-by-state model based on historical data from the US Census Bureau. Our complete Global Population dataset is available in excel format from the 'Downloads' section.