| Year | Value | | 2022 | 0.76465339190692 | | 2021 | 0.77626042644676 | | 2020 | 0.86371534384839 | | 2019 | 0.69632432476046 | | 2018 | 0.65287656979399 | | 2017 | 0.66568455676088 | | 2016 | 0.66475047541252 | | 2015 | 0.65134108284021 | | 2014 | 0.63489833846369 | | 2013 | 0.71263624239087 | | 2012 | 0.66900171043432 | | 2011 | 0.6947822576576 | | 2010 | 0.68722016593328 | | 2009 | 0.73179337674355 | | 2008 | 0.72248441226519 | | 2007 | 0.71823232366341 | | 2006 | 0.75380847787493 | | 2005 | 0.83306403652778 | | 2004 | 0.88892507460693 | | 2003 | 0.92663041940086 | | 2002 | 0.95638834976495 | | 2001 | 0.99188008013839 | | 2000 | 1.0292801174596 | | 1999 | 1.0862122054681 | | 1998 | 1.1852039013937 | | 1997 | 1.2208641034212 | | 1996 | 1.2837568015836 | | 1995 | 1.3558108825235 | | 1994 | 1.3322840940318 | | 1993 | 1.3669643451841 | | 1992 | 1.5237092723954 | | 1991 | 1.5378248855308 | | 1990 | 1.5721471875724 | | 1989 | 1.5241653668033 | | 1988 | 1.5648052643261 | | 1987 | 1.5618660554213 | | 1986 | 1.6610219514039 | | 1985 | 1.8249718683211 | | 1984 | 1.7012483029568 | | 1983 | 1.7488055893282 | | 1982 | 1.7281945112719 | | 1981 | 1.6628022214327 | | 1980 | 1.6786065458632 | | 1979 | 2.0397994260305 | | 1978 | 1.9673644305258 | | 1977 | 2.0220865628644 | | 1976 | 2.1625810087349 | | 1975 | 1.90075273804 | | 1974 | 1.87597448618 | | 1973 | 1.8614485622021 | | 1972 | 1.9681261245823 | | 1971 | 2.0525268216904 | | 1970 | 2.1033474880053 | | 1969 | 2.1979237053873 | | 1968 | 2.176517571885 | | 1967 | 2.3823738450604 | | 1966 | 2.5307933593451 | | 1965 | 2.4679592507394 | | 1964 | 2.5358556973163 | | 1963 | 2.5163366819468 | | 1962 | 2.5675675675676 | | 1961 | 2.4690770694577 | | 1960 | 2.3414503612523 |
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