Source: U.S. Bureau of Economic Analysis
Release: Gross Domestic Product
BEA Account Code: N4516C
For more information about this series, please see http://www.bea.gov/national/."
U.S. Bureau of Economic Analysis, Self-employed persons: Professional and business services [N4516C0A173NBEA], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/N4516C0A173NBEA, December 16, 2017.