Year	current US$
1971	0.2246395494063578
1972	3.226685312688411
1973	5.92411384369137
1974	7.284523503885977
1975	14.125504423184926
1976	6.43898248808582
1977	9.885357682638213
1978	11.982868750550729
1979	13.700468634811935
1980	14.646890273000883
1981	12.237154500096779
1982	14.726045941365522
1983	10.909493053192877
1984	11.857048829600249
1985	10.241342511980026
1986	13.106411991849416
1987	16.11101478336367
1988	13.561454976818757
1989	14.134885142641584
1990	16.695653219817764
1991	14.758130228506612
1992	13.468335705692521
1993	10.274931818527952
1994	11.977263378642116
1995	8.770529835495111
1996	8.048925710027834
1997	7.0727261447402405
1998	7.877332348769061
1999	7.932084641415936
2000	7.557201672308269
2001	6.975367480285339
2002	6.019092528225458
2003	9.536699372925352
2004	10.240671986547492
2005	8.882243915303734
2006	7.206256540720438
2007	6.160781462271407
2008	7.855176079436648
2009	6.671605902488439
2010	8.944806037607744
2011	9.570004671303877
2012	14.162935479538454
2013	17.097888147011474
2014	15.533596527547067
2015	16.428498461061775
2016	15.85146863719267
2017	23.373987051403535
2018	18.601456410075507
2019	26.472268342072233
2020	32.103388214275824
2021	30.049731457985864
2022	30.334132199860512