Source: U.S. Bureau of Economic Analysis
Release: Gross Domestic Product
BEA Account Code: PB000009
The arithmetic average of gross domestic product and of gross domestic income, deflated by the implicit price deflator for GDP.
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, Real Average of GDP and GDI [PB0000091Q225SBEA], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/PB0000091Q225SBEA, August 21, 2018.