| Year | Value | | 2022 | 1.1288201054869 | | 2021 | 1.1966469857329 | | 2020 | 1.2446895087522 | | 2019 | 1.2441008233029 | | 2018 | 1.1539575346446 | | 2017 | 1.1275811077133 | | 2016 | 1.2259003810155 | | 2015 | 1.2085171068153 | | 2014 | 1.1364432719278 | | 2013 | 1.1137294292233 | | 2012 | 1.1808972336465 | | 2011 | 1.217668949476 | | 2010 | 1.1843840170018 | | 2009 | 1.0289395484523 | | 2008 | 0.93821529163328 | | 2007 | 0.99709196441371 | | 2006 | 0.98983883698297 | | 2005 | 0.97281009026611 | | 2004 | 0.99885977372525 | | 2003 | 1.0026330976062 | | 2002 | 1.0483664626004 | | 2001 | 1.2884227755166 | | 2000 | 1.3571191812402 | | 1999 | 1.5848343910461 | | 1998 | 1.5675351983922 | | 1997 | 1.5716679258746 | | 1996 | 1.5390735944898 | | 1995 | 1.5666931407425 | | 1994 | 1.529023663866 | | 1993 | 1.4293905149652 | | 1992 | 1.3605031498535 | | 1991 | 1.2144228020077 | | 1990 | 1.2231650262937 | | 1989 | 1.2908618013077 | | 1988 | 1.2463880971746 | | 1987 | 1.1682325387956 | | 1986 | 1.1121916755577 | | 1985 | 1.0542727837491 | | 1984 | 1.1780419604011 | | 1983 | 1.2706737119892 | | 1982 | 1.0608696853732 | | 1981 | 0.91583169130867 | | 1980 | 0.85742085931126 | | 1979 | 0.9342929610521 | | 1978 | 1.2689851807321 | | 1977 | 1.569977813129 | | 1976 | 1.5236789752651 | | 1975 | 0.84478333092137 | | 1974 | 0.60430349176937 | | 1973 | 0.65672053667347 |
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