Year	base year varies by country
1975	3.297186234253969
1976	3.5656759500005486
1977	3.9200664420857527
1978	4.453293136377337
1979	5.171849054808165
1980	6.106869932111332
1981	6.923999470579124
1982	7.651313791619893
1983	8.457366625188142
1984	9.257587837965763
1985	9.424322286552002
1986	10.172279564821931
1987	10.752308163981457
1988	13.512665637949326
1989	16.510550370761422
1990	17.781653120871525
1991	18.901548934076384
1992	20.284059762008987
1993	22.456912067391663
1994	24.97915899509052
1995	26.71707486052936
1996	27.9073230836875
1997	29.4202548486785
1998	35.79627736849623
1999	37.4359098828979
2000	43.52319631049293
2001	48.86647961673541
2002	51.2666295183464
2003	55.013296073381014
2004	58.780345938954426
2005	63.3207387339292
2006	65.24086751176958
2007	67.44894420648103
2008	67.64225029523713
2009	74.37217657904316
2010	77.52051585238371
2011	82.91400326086865
2012	86.43650331855113
2013	89.31954305421522
2014	93.20810389970086
2015	96.66359808106739
2016	99.99999993334153
2017	103.48993467104694
2018	107.71004760862834
2019	109.16921812650004
2020	109.60397090209723
2021	115.8411284331367
2022	130.28779108413917
2023	134.89894822926684