Year	current US$
1970	0.500676511503937
1971	0.5740261061119856
1972	0.648709518079198
1973	0.22895723737514398
1974	0.13715117985244085
1975	0.15818068472688915
1976	0.33718880932454504
1977	0.24621132735787596
1978	0.460112033809161
1979	1.5134231977696029
1980	2.447256326848434
1981	1.8487137544659793
1982	1.6302321324669982
1983	0.8870655864992009
1984	0.5931732065609896
1985	0.4396712823853921
1986	0.8215359071749416
1987	0.9063546569937706
1988	0.6807933669441827
1989	0.3649488172917225
1990	3.0718462900064356
1991	4.778261599403721
1992	2.0479390093416643
1993	2.78111748130999
1994	4.364026693461466
1995	6.245881179485951
1996	6.584242290049357
1997	5.707537810781917
1998	6.370650239392317
1999	9.672137558642655
2000	9.627049449664817
2001	9.706606995121792
2002	12.549975174743325
2003	10.297270225093444
2004	10.814679085213022
2005	11.178200359016248
2006	13.540503774072457
2007	12.931648150449035
2008	15.807455238364522
2009	17.004770376111317
2010	16.002497797719794
2011	23.094813807967856
2012	21.964082857282968
2013	19.542021271893493
2014	22.520948985991804
2015	18.539862232778887
2016	21.102132337500954
2017	21.062664606902057
2018	17.54599717604548
2019	15.329220259723256
2020	22.967252211479085
2021	20.39868314330678