Year	constant 2015 US$
1977	31362723.272785764
1978	40314174.16335163
1979	33214733.845209442
1980	28735943.60385707
1981	40235036.27202808
1982	37081403.44309804
1983	37651499.89020816
1984	44327203.76775132
1985	48294848.01447561
1986	48410286.25437068
1987	43802842.55333215
1988	64971660.694568634
1989	61209937.22478135
1990	71189552.8746821
1991	61512008.05694796
1992	67480609.33212274
1993	62234947.20257577
1994	40212674.25566058
1995	58631037.57365824
1996	55978198.16073712
1997	46431655.04411229
1998	50637253.18602952
1999	49228500.71591882
2000	52834371.45378571
2001	48665730.07189706
2002	54028720.616173394
2003	49672624.26850388
2004	48481622.51621943
2005	48829381.232499406
2006	49482160.01485245
2007	53899388.86218498
2008	52394068.68242959
2009	63689447.61076395
2010	48495147.40552541
2011	46967375.909522094
2012	47606697.42701569
2013	49695954.7025567
2014	51252568.02500501
2015	49240740.74074073
2016	52331177.947156794
2017	54332861.56444159
2018	57396248.99224569
2019	56449506.7408272
2020	57362436.76898075
2021	40513805.9160582
2022	38021845.06143168
2023	36906041.69368847