Year	current US$
1970	3.519251530824162
1971	3.8629174013425303
1972	4.192079183786917
1973	4.980174194523574
1974	7.405726806880827
1975	9.834846287518916
1976	8.866566254447111
1977	10.180753695294264
1978	13.324594542801442
1979	16.711744364685135
1980	18.971306492229225
1981	17.98752328088328
1982	18.05309796930591
1983	16.938686056224892
1984	17.015857545745934
1985	18.69287653335792
1986	22.299063338640835
1987	25.03011304943112
1988	27.71776327769187
1989	28.515846473294335
1990	32.81700673050115
1991	31.567013891108147
1992	33.06884277070106
1993	29.695686564281452
1994	31.209532836238864
1995	30.05590696943729
1996	24.664365284013147
1997	21.433639077511764
1998	20.909700162378208
1999	18.739598934715723
2000	17.943915405673867
2001	19.176696293921037
2002	24.94691784789844
2003	31.696989007535777
2004	32.76772454248764
2005	40.12647484315346
2006	49.25562405443758
2007	40.91079278342457
2008	43.48987665216268
2009	45.986374200226734
2010	45.83182327971724
2011	47.24248910087265
2012	44.9321883460569
2013	45.349523261421254
2014	41.394932940162946
2015	39.80707619381853
2016	37.54588155604723
2017	41.166158575165625
2018	40.74935761268385
2019	41.47139152037454
2020	51.88451469135515
2021	45.699543080553084