I am not too familiar with the US tax system or the history of tax revenues. Anyway I came across two trends of historical data that are quite different, from the OECD and the Office of Management and Budget. Have I missed some obvious difference in what is being represented, and if not why the difference? https://en.wikipedia.org/wiki/Hause...Receipts_as_a_Percentage_of_GDP_1945–2015.jpg http://www.usnews.com/dims4/USNEWS/...ages/master/52244/widemodern_taxes_012214.jpg Cheers