| Year | Value | | 2022 | 0.2713695777757 | | 2021 | 0.84329467800503 | | 2020 | 0.7012115707333 | | 2019 | 0.69523914013607 | | 2018 | 0.77913839619223 | | 2017 | 0.88621557329239 | | 2016 | 0.9138853322266 | | 2015 | 0.81862634094585 | | 2014 | 0.94174335423422 | | 2013 | -1.0710348032908 | | 2012 | -1.2403591532927 | | 2011 | -1.82076700208 | | 2010 | -2.0813050898811 | | 2009 | -1.6510249675912 | | 2008 | -1.0509395443743 | | 2007 | 0.81617550658298 | | 2006 | 0.91727295748817 | | 2005 | -1.0805714569117 | | 2004 | -1.0913129555742 | | 2003 | 0.96640080123756 | | 2002 | -1.1618382239436 | | 2001 | -1.2914869435487 | | 2000 | 0.96393540709237 | | 1999 | 0.81396120387219 | | 1998 | 0.94291893712221 | | 1997 | 0.99676228875754 | | 1996 | -1.1263750958234 | | 1995 | -1.4258108121573 | | 1994 | -1.6738287007511 | | 1993 | -1.9719320957036 | | 1992 | -1.376795065835 | | 1991 | 0.47311469404067 | | 1990 | 0.14273639758179 | | 1989 | 0.50827219996574 | | 1988 | 1.0170888264493 | | 1987 | 1.0213856199337 | | 1986 | 0.81174239094463 | | 1985 | 0.65459334444963 | | 1984 | 0.62787277205787 | | 1983 | 0.58817315051127 | | 1982 | 0.46169759042584 | | 1981 | 0.30689003602013 | | 1980 | 0.22911115490876 | | 1979 | 0.32103154069156 | | 1978 | 0.51567505283918 | | 1977 | 0.56835600171116 | | 1976 | 0.60315348773921 | | 1975 | 0.774284540119 | | 1974 | 0.88057350313793 | | 1973 | 0.83737491515697 | | 1972 | 0.80825022576466 | | 1971 | 0.72747896458402 | | 1970 | 0.68013252315289 | | 1969 | 0.83801096914203 | | 1968 | 0.96864669826735 | | 1967 | 0.78540036839363 | | 1966 | 0.76049972436478 | | 1965 | 1.1226463961967 | | 1964 | 1.3345685999914 | | 1963 | 1.3356130977194 | | 1962 | 1.333809316627 | | 1961 | 1.4836267510551 |
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