Year	current US$
1960	0.8515205344219756
1961	0.8042265190127916
1962	0.8374762417790241
1963	0.8333986801707353
1964	0.7209633762356268
1965	0.9450914186501034
1966	1.1051358572135896
1967	1.23333377531939
1968	1.240647663728768
1969	1.354665514106002
1970	1.3691370004445163
1971	1.542465921217017
1972	1.703042976496689
1973	1.7490233780981175
1974	2.0353135740626196
1975	1.7401645610155059
1976	1.5037766047368926
1977	1.502407080160231
1978	1.949822767498718
1979	2.2594892387771877
1980	2.5131344445620485
1981	2.773724771125316
1982	2.4521867917815636
1983	2.4453163077160815
1984	2.4603229158519637
1985	2.4488789139580263
1986	3.0247403597992224
1987	3.5225088729182197
1988	4.015315641044232
1989	4.1556898824871995
1990	4.432383200789192
1991	4.225600718691906
1992	5.423814689288275
1993	5.124317673952237
1994	5.16271425578473
1995	5.379786981373861
1996	4.296295948023299
1997	3.5692591346099594
1998	4.358722499387582
1999	5.016325746906285
2000	4.024302584019691
2001	3.4282057471834997
2002	3.3585417885351725
2003	3.235802392790688
2004	3.1648573756403438
2005	4.345056399550346
2006	3.516649360403805
2007	3.517612611924648
2008	3.5985454080810984
2009	3.7882264832885215
2010	4.271049742966142
2011	3.3692258160596413
2012	3.9524254003026345
2013	5.311460511647613
2014	4.167805937162684
2015	3.7156128864597813
2016	3.3410036262820118
2017	3.615904244613602
2018	3.536387448903051
2019	3.024805876764335
2020	5.382928699937525
2021	4.467667600422349
2022	4.028109286799841