Year	current US$
1970	1.8266402778233628
1971	1.952555741251933
1972	1.9683421617707484
1973	2.5567264147155124
1974	3.5780409760666423
1975	4.625932964172153
1976	4.359990697858835
1977	4.405742225334076
1978	5.192115131524412
1979	6.12772159648311
1980	7.275152320459987
1981	6.85264318783204
1982	6.360341722025039
1983	5.793596654095761
1984	5.720240044802331
1985	5.99504706679604
1986	6.826176428079252
1987	7.538817088534332
1988	7.907411382743636
1989	8.05499440117543
1990	10.649194821041418
1991	10.969786691115992
1992	10.182477084224924
1993	9.00029806738169
1994	9.812726153939893
1995	9.389374661369494
1996	8.34211544198274
1997	7.188498316174833
1998	7.462506050395196
1999	7.601022847880753
2000	6.902142329917043
2001	7.438784273187964
2002	8.345879406217769
2003	9.676247385358101
2004	10.46498300542997
2005	15.475192234990718
2006	14.43689793807111
2007	13.762959320673543
2008	14.940289443214352
2009	14.64169566578146
2010	14.728860535377201
2011	15.655927161083921
2012	15.286730080441574
2013	16.744500195847813
2014	16.232027751901164
2015	15.320291562932244
2016	15.718799789367361
2017	16.751037669355778
2018	16.811143821979453
2019	16.113155403822912
2020	20.085414331442703
2021	19.59520704613482