Year	constant 2015 US$
1980	467.54634746697144
1981	470.47196763423403
1982	452.2141201645721
1983	445.22821368813464
1984	423.0346043628618
1985	451.89724464090426
1986	420.3713435034837
1987	420.5062339297389
1988	414.8504733632594
1989	394.3697889724237
1990	373.1796180358878
1991	355.91488146373626
1992	462.17608662971344
1993	494.52372928666944
1994	555.8467554060047
1995	628.8802503007033
1996	1008.3283804575132
1997	2424.8285165541847
1998	2886.1530626728663
1999	3486.79895005658
2000	3941.6635354986365
2001	6132.84731716448
2002	6987.942670979024
2003	7604.480723140122
2004	10028.354382915446
2005	11188.44858045232
2006	11508.925961928384
2007	12660.905512196401
2008	14222.548886248846
2009	13740.840017434648
2010	11933.311075078134
2011	12155.818780406064
2012	12625.29596577615
2013	11614.00294699182
2014	11200.810716702046
2015	9788.983803697178
2016	8594.450219238393
2017	7818.0535900282075
2018	7079.650526220912
2019	6472.070882636948
2020	5995.905844461843
2021	5905.3447996211235
2022	5976.900107500371
2023	5506.005040825489