Year	current US$
1970	3.6189101892622504
1971	3.932228233195575
1972	4.486253847839949
1973	6.132408262901532
1974	9.236413318555373
1975	11.839619615139837
1976	10.844235555552071
1977	11.668462848108097
1978	13.860586640738237
1979	18.250909158338555
1980	20.79913154099174
1981	18.548066062429793
1982	17.942794535843532
1983	15.782624711050051
1984	15.61220793082501
1985	16.266572035108055
1986	19.175442200738942
1987	21.283820739804224
1988	22.397237963757046
1989	22.645052410959014
1990	26.370040203952875
1991	25.738197676192776
1992	25.331124515900637
1993	22.41478810992637
1994	25.12256946244454
1995	23.363989860895394
1996	19.701462418339815
1997	17.125918907209257
1998	16.975087200886307
1999	15.893071776084357
2000	15.053760342357831
2001	17.517936748006164
2002	20.67149202208411
2003	24.997457561908202
2004	26.577845188085835
2005	31.97569320234516
2006	38.07706280438064
2007	34.83904618283077
2008	35.79570222701608
2009	39.91133194941362
2010	41.860019688738625
2011	42.43733357071737
2012	41.894064183796
2013	45.03360514216744
2014	41.977215030372555
2015	41.16545886108271
2016	41.585382169034794
2017	45.93264760953196
2018	47.74551432314263
2019	46.972192140802925
2020	55.92556621275038
2021	50.90266211113505