> The numbers for the map come from historian Angus Maddison who uses Sestertius records to find wheat equivalent figure for national disposable income and make

> The numbers for the map come from historian Angus Maddison who uses Sestertius records to find wheat equivalent figure for national disposable income and makes comparisons based off that. Links to several of Angus Maddison books, I assume it is this: Contours of the World Economy 1-2030 AD: Essays in Macro-Economic History