Source: U.S. Bureau of Economic Analysis
Release: Gross Domestic Product
BEA Account Code: Y804RC
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, Imports of services: Transport [Y804RC1A027NBEA], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/Y804RC1A027NBEA, June 22, 2018.