a    2017
b    2018
c    Data classified according to ISIC Rev. 4.
d    Including taxes less subsidies on production and imports.
e    Estimate.
f    Urban areas.
g    2016
h    Excluding water and waste management.
i    2014
j    Including the trade of the U.S. Virgin Islands and Puerto Rico but excluding shipments of merchandise between the United States and its other possessions (Guam and American Samoa). Data include imports and exports of non-monetary gold.
k    Data refers to a 5-year period preceding the reference year.
l    2015
m    Data as at the end of December.
n    Population aged 3 years and over.
o    Do not correspond exactly to Frascati Manual recommendations.
p    Provisional data.
q    2004
r    Including overseas territories.
s    Oil and coal trade statistics include overseas territories.
t    Break in the time series.
u    Development Assistance Committee member (OECD).