Data is important for an economist, one of the main ones is population. UN provides a set of projections for the earthling population for the next century (up to 2100). In addition to historical data (1950-2010), several scenarios are explored to estimate the world population growth. The data is also categorized into gender and age, in addition to its country-level detail
Additional document: Population up to 2300! https://www.un.org/esa/population/publications/longrange2/WorldPop2300final.pdf
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