| Year | Value | | 2022 | 0.76170187729686 | | 2021 | 0.10579919426408 | | 2020 | 0.48850213183858 | | 2019 | 0.7177156371035 | | 2018 | 0.4379829937287 | | 2017 | 0.23458792296856 | | 2016 | 0.084430150068074 | | 2015 | 0.077588861590047 | | 2014 | 0.29895105908804 | | 2013 | 0.32766903957969 | | 2012 | 0.064925962561723 | | 2011 | 0.35533839647143 | | 2010 | 0.4604083050513 | | 2009 | 0.88573598057307 | | 2008 | 1.5953304990637 | | 2007 | 1.8510813084518 | | 2006 | 1.6903525562611 | | 2005 | 1.6893490471203 | | 2004 | 1.7254663034483 | | 2003 | 1.8084544681835 | | 2002 | 1.4125954047578 | | 2001 | 0.69406808433446 | | 2000 | 0.44713701453583 | | 1999 | 0.40532302552285 | | 1998 | 0.41384748111397 | | 1997 | 0.41911951720212 | | 1996 | 0.4165157982128 | | 1995 | 0.44136574953787 | | 1994 | 0.47610055516917 | | 1993 | 0.51854352086642 | | 1992 | 0.48975790543999 | | 1991 | 0.25452742455104 | | 1990 | 0.10182884260704 | | 1989 | 0.15677619761846 | | 1988 | 0.21206499926918 | | 1987 | 0.25932906320183 | | 1986 | 0.2987823668144 | | 1985 | 0.36236556491649 | | 1984 | 0.41525570237357 | | 1983 | 0.48718321057366 | | 1982 | 0.6003901372404 | | 1981 | 0.71087801051254 | | 1980 | 0.80296356191084 | | 1979 | 0.88158450134584 | | 1978 | 0.96287655038845 | | 1977 | 1.0291318085915 | | 1976 | 1.0568517247231 | | 1975 | 1.0812936030828 | | 1974 | 1.0926076103807 | | 1973 | 1.1049376041377 | | 1972 | 1.1041365897105 | | 1971 | 1.2050848329396 | | 1970 | 1.1106314487677 | | 1969 | 0.98543055957826 | | 1968 | 1.3076557858119 | | 1967 | 1.230665818156 | | 1966 | 1.024027852338 | | 1965 | 1.0858447420938 | | 1964 | 0.99369642623311 | | 1963 | 0.87704325165921 | | 1962 | 0.92003228652971 | | 1961 | 0.92901553460921 |
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