Year	base year varies by country
1960	7.67541505389871
1961	8.04677318792195
1962	7.70427828448476
1963	8.01369931825919
1964	8.16127558231803
1965	8.65305078205651
1966	8.73245712461745
1967	9.12814903162298
1968	9.39885121774008
1969	9.86439176821252
1970	10.3525397965007
1971	10.9170494947082
1972	11.5150506684578
1973	12.1208030514691
1974	14.1094091650741
1975	16.1037583908632
1976	18.633735984586
1977	20.7455100269787
1978	22.4106266267597
1979	24.3533021549925
1980	26.6718274454239
1981	29.3914891424752
1982	32.5046817545228
1983	35.2747167005983
1984	37.8770307004559
1985	40.3324635891319
1986	43.391495932199
1987	46.7399905597366
1988	49.6561417124164
1989	53.2315190644382
1990	56.3265427570516
1991	58.0168643840187
1992	59.0826119408128
1993	60.1572322138419
1994	61.2266573216824
1995	62.3931240577118
1996	63.4817518679077
1997	63.9199763917176
1998	64.9613771151341
1999	65.8179357078147
2000	67.0784366422489
2001	69.6886549550684
2002	71.6401666085323
2003	73.6874411589936
2004	74.7915580684161
2005	76.4160587521948
2006	78.880952722877
2007	81.473909387877
2008	84.0854464585841
2009	86.8430816131478
2010	88.1418220081072
2011	90.1982085431213
2012	91.8899505387728
2013	93.7314951315586
2014	95.7358174532469
2015	97.4300880294607
2016	99.2344576534119
2017	100
2018	101.421994230899