Year	constant 2015 US$
1970	13587.262704117913
1971	14004.24500980568
1972	14600.132139684867
1973	15318.709455230866
1974	15306.280919094335
1975	15092.431223092852
1976	15737.581335871746
1977	16124.075931448424
1978	16696.638678615207
1979	17171.082446350916
1980	17080.794344080445
1981	16784.01105102128
1982	16861.154667847964
1983	17119.786098855562
1984	17499.51120080693
1985	17912.688457046177
1986	18822.253477410966
1987	19361.457817782077
1988	20190.88598847179
1989	20855.66481856983
1990	21527.857481137686
1991	21890.938502634104
1992	22133.750537334603
1993	21860.536754463406
1994	22305.183269925128
1995	22858.261580921688
1996	23227.767767761856
1997	23808.38547745953
1998	24563.061961215455
1999	25248.22284004571
2000	25795.957108306728
2001	26215.848658761777
2002	26288.363551543913
2003	26359.16758924971
2004	26907.673177466513
2005	27116.819664803323
2006	27822.899760347413
2007	28464.648648230086
2008	27979.83159496951
2009	26827.479974500995
2010	27237.106102865342
2011	27568.92281951165
2012	27158.419457294745
2013	27112.231806460688
2014	27500.305084983866
2015	28094.98436127907
2016	28780.195585709498
2017	29393.99998013047
2018	29831.267864765934
2019	30187.194958107986
2020	27835.35158186534
2021	29377.656774740994