Source: U.S. Bureau of Economic Analysis
Release: Gross Domestic Product
BEA Account Code: PA000009
A Guide to the National Income and Product Accounts of the United States (NIPA) - (http://www.bea.gov/national/pdf/nipaguid.pdf)
U.S. Bureau of Economic Analysis, Average of GDP and GDI [PA0000091Q225SBEA], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/PA0000091Q225SBEA, September 26, 2018.