Year	current US$
1970	5.221839208614989
1971	5.122601435726133
1972	4.550190605303039
1973	4.4467432228141845
1974	6.057264469590832
1975	8.187078951771895
1976	9.395815222462032
1977	7.098014154676283
1978	7.959389704634349
1979	9.024620878656108
1980	12.26139516312029
1981	10.118523997140963
1982	10.426219052372353
1983	8.607571109608537
1984	8.833641508465076
1985	8.13465236743633
1986	9.162596915241112
1987	9.256127696728099
1988	12.337099368932654
1989	14.152487668509814
1990	13.755698502768517
1991	13.347155314668903
1992	14.242669489721036
1993	12.023020084382818
1994	13.489575404995447
1995	9.931883734455026
1996	10.257229173887152
1997	9.085044081379229
1998	8.51597950922391
1999	7.322747284155852
2000	7.220506968633493
2001	10.006978639829462
2002	10.999021572065237
2003	9.588175027231292
2004	11.085793313373474
2005	28.03339155164678
2006	40.83245744617959
2007	20.295813368593638
2008	14.36615593133303
2009	19.05850032096151
2010	22.573896085475354
2011	22.72250629144888
2012	20.018236947890756
2013	22.369398843476578
2014	23.23656400767256
2015	22.270711299544548
2016	19.83061712496569
2017	21.793101854063842
2018	20.750061610622556
2019	23.19233567788117
2020	27.361952193555815
2021	25.47227224053942