Year	current US$
1970	0.39124059630984465
1971	0.4502117499918801
1972	0.4916760592566231
1973	0.39961856421306147
1974	0.3638364155566853
1975	0.361498861265639
1976	0.35556609229006475
1977	0.3789716204191108
1978	0.3044745966368459
1979	0.28848848002386895
1980	0.2657123606647086
1981	0.500206479907355
1982	0.14834810672326762
1983	0.1425061392012363
1984	0.07826701970377566
1985	0.11196945478892284
1986	0.0944648585345676
1987	0.11770174747370019
1988	0.12870709893112084
1989	0.25536862423337864
1990	0.15865376388741884
1991	0.17161667305990477
1992	0.029704730601425703
1993	0.1819732470417574
1994	0.582438387541819
1995	1.240559518741088
1996	1.070187440218632
1997	0.9321858467115641
1998	1.0618715889082415
1999	1.383976910801525
2000	0.9230466980459201
2001	0.9194092563784775
2002	0.8057195483516493
2003	0.7391980190795578
2004	0.9002925029054267
2005	1.1687223223001695
2006	1.309126609567913
2007	1.3122196140013622
2008	1.4797787078853715
2009	1.371552538428381
2010	1.4914039620128745
2011	1.5085618920816957
2012	1.4141494747592995
2013	1.3981788765004421
2014	2.2145875863800315
2015	2.2512289904305423
2016	4.215234533533209
2017	1.9128012121225206
2018	2.221088389492308
2019	2.080768155637579
2020	3.719334204124999
2021	2.400552427843524