| Year | Value | | 2022 | 0.81479573625685 | | 2021 | 0.76550103949659 | | 2020 | 0.73067619504738 | | 2019 | 0.71331366844433 | | 2018 | 0.73663397517252 | | 2017 | 0.93315588873865 | | 2016 | 1.0920311738725 | | 2015 | 1.1383371524774 | | 2014 | 1.2201039734329 | | 2013 | 1.1498797578123 | | 2012 | 1.0618193288679 | | 2011 | 1.1118789426321 | | 2010 | 1.0415580576588 | | 2009 | 1.2494846312738 | | 2008 | 1.2706180738578 | | 2007 | 0.89369097782313 | | 2006 | 0.62755847334613 | | 2005 | 0.64060154024349 | | 2004 | 0.68742596023301 | | 2003 | 0.74191960337232 | | 2002 | 0.7564691458381 | | 2001 | 0.63277123801843 | | 2000 | 0.56195461740016 | | 1999 | 0.47691993128564 | | 1998 | 0.29713576574006 | | 1997 | 0.24089121015565 | | 1996 | 0.44163640670635 | | 1995 | 0.66824232623432 | | 1994 | 0.79715841102482 | | 1993 | 0.91071556578847 | | 1992 | 1.1025210722909 | | 1991 | 1.2498260244163 | | 1990 | 1.0268730721952 | | 1989 | 0.80853605555095 | | 1988 | 0.73494305612324 | | 1987 | 0.62811575454302 | | 1986 | 0.52039161133616 | | 1985 | 0.44144266764139 | | 1984 | 0.35911165241451 | | 1983 | 0.42878792000241 | | 1982 | 0.58429167538567 | | 1981 | 0.54706491013226 | | 1980 | 0.39707441863761 | | 1979 | 0.20080949151164 | | 1978 | 0.0089788100144072 | | 1977 | 0.33901090648565 | | 1976 | 0.57159575476383 | | 1975 | 0.04373804341749 | | 1974 | 0.53852083285567 | | 1973 | 0.73822552946645 | | 1972 | 0.76247999040952 | | 1971 | 0.52479184164869 | | 1970 | 0.72240383062557 | | 1969 | 1.125420460311 | | 1968 | 1.2592563480889 | | 1967 | 1.2390472466302 | | 1966 | 1.0451517426159 | | 1965 | 1.1548425141922 | | 1964 | 1.6542582451453 | | 1963 | 2.1376628211307 | | 1962 | 2.5350125367586 | | 1961 | 1.9786150590587 |
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