Year	current US$
1970	4.470091912699109
1971	4.8418785488673555
1972	4.792561441392757
1973	5.983313493133847
1974	8.656710100802538
1975	10.479640468957836
1976	9.786391462440504
1977	10.402703449723026
1978	14.127519262457655
1979	16.0347671785963
1980	17.149751721300422
1981	16.323779616906574
1982	15.652418792320134
1983	14.472452235656887
1984	16.102855006445346
1985	16.200329393768722
1986	21.576053817964603
1987	22.724371041184945
1988	25.648962523860728
1989	29.209025919457716
1990	31.31252059626635
1991	30.911301232423668
1992	30.32127463602988
1993	28.248066658541017
1994	33.12012303827169
1995	29.304614987256134
1996	27.69423146066077
1997	21.241543528575914
1998	22.092514322325126
1999	18.18660080432304
2000	15.018143103061519
2001	16.97845408090199
2002	21.924965945095213
2003	22.236690541030832
2004	27.262221769150436
2005	46.36400571486964
2006	63.92314832473567
2007	38.620281744916014
2008	37.19732657931174
2009	41.03020684297888
2010	43.063833385982434
2011	38.70987117567315
2012	41.21542641370272
2013	36.429349556488226
2014	37.021330328565746
2015	35.85281429964165
2016	32.95605604642104
2017	36.919603206567054
2018	37.44276250785866
2019	40.569610440446795