Year	current US$
1970	1692.6623224612051
1971	1864.8893891953696
1972	2425.5503297118803
1973	3263.7910951344443
1974	3583.745727475881
1975	3877.4824270215468
1976	4339.494095388393
1977	5295.6492715120485
1978	7402.388027704011
1979	7612.651540516421
1980	7869.365614871866
1981	8531.670465424397
1982	7882.814807446759
1983	8564.064758282833
1984	9025.199744820582
1985	9518.30455558943
1986	14023.725828232167
1987	16977.224514504254
1988	20502.599690627438
1989	20145.074904844845
1990	20510.03618448574
1991	23156.460763039755
1992	24932.55980731525
1993	28050.30568496543
1994	31293.521187714694
1995	34830.748925500986
1996	31065.901673894732
1997	28128.501040038715
1998	25348.864560789163
1999	28509.35820435991
2000	30664.41044119873
2001	26963.275916349718
2002	25619.91822502656
2003	27744.272425242958
2004	30235.081846415025
2005	29916.37675491974
2006	28494.95544988604
2007	28372.357660045313
2008	31016.566917337637
2009	31604.276624600345
2010	34955.31619527812
2011	38054.34220293454
2012	38500.58418554717
2013	32389.62683030672
2014	30542.977693877325
2015	28006.306867406423
2016	31470.252917531085
2017	31134.54194313644
2018	31788.516090155823
2019	32283.770717092542
2020	31293.415999186764
2021	30520.07048257162