Year | Value | 2023 | 1.3841027235013 | 2022 | 1.4035293256081 | 2021 | 1.4426894420878 | 2020 | 1.5022865633901 | 2019 | 1.5576608647888 | 2018 | 1.6025937293561 | 2017 | 1.6428612539906 | 2016 | 1.6851989161085 | 2015 | 1.7396127340918 | 2014 | 1.8005649605921 | 2013 | 1.8526117702003 | 2012 | 1.8993890613377 | 2011 | 1.9488494482456 | 2010 | 2.0333227022972 | 2009 | 2.0832551019731 | 2008 | 2.0604351921045 | 2007 | 2.1689675047578 | 2006 | 1.9584904050681 | 2005 | 1.5664849824679 | 2004 | 1.5375601063266 | 2003 | 2.2305415548786 | 2002 | 3.0969609248384 | 2001 | 3.1603460100549 | 2000 | 3.1398345323241 | 1999 | 3.493826001548 | 1998 | 4.0168210011243 | 1997 | 3.5558392771835 | 1996 | 2.384027029156 | 1995 | 1.0103405243592 | 1994 | 2.009004234136 | 1993 | -1.8972474053385 | 1992 | 0.80853068169341 | 1991 | 8.5220417829905 | 1990 | 10.197122430931 | 1989 | 7.7095108266814 | 1988 | 6.4189235124012 | 1987 | 6.3736171152188 | 1986 | 5.7079910307629 | 1985 | 4.7379021343416 | 1984 | 3.8486396717787 | 1983 | 3.4894576359265 | 1982 | 3.953212680224 | 1981 | 5.1537728394003 | 1980 | 6.7615956445888 | 1979 | 8.3813467851289 | 1978 | 9.5155566019787 | 1977 | 9.8466211539056 | 1976 | 9.4609194280128 | 1975 | 8.5986344997494 | 1974 | 7.6380148380247 |
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