| Year | Value | | 2022 | 1.0233919787895 | | 2021 | 1.0514843122207 | | 2020 | 1.0531601791461 | | 2019 | 1.0435841266992 | | 2018 | 1.1178970270223 | | 2017 | 1.1916294240897 | | 2016 | 1.2231702343059 | | 2015 | 1.2530582728991 | | 2014 | 1.3080629397791 | | 2013 | 1.3442338429362 | | 2012 | 1.3537724665738 | | 2011 | 1.3426655434854 | | 2010 | 1.3083515451046 | | 2009 | 1.2811062462056 | | 2008 | 1.2800372014876 | | 2007 | 1.2877219197481 | | 2006 | 1.3094792438627 | | 2005 | 1.3190526878203 | | 2004 | 1.2458784781145 | | 2003 | 1.2192626651887 | | 2002 | 1.2767055848866 | | 2001 | 1.3070906776195 | | 2000 | 1.3305629274657 | | 1999 | 1.376402314954 | | 1998 | 1.4304087322666 | | 1997 | 1.4634552532715 | | 1996 | 1.4927847173982 | | 1995 | 1.5056818185337 | | 1994 | 1.5181475634882 | | 1993 | 1.5861344009723 | | 1992 | 1.6376756623396 | | 1991 | 1.6839715402736 | | 1990 | 1.7353448117643 | | 1989 | 1.7862420355158 | | 1988 | 1.8751616581516 | | 1987 | 1.975967620863 | | 1986 | 2.1673752252432 | | 1985 | 2.3456498463151 | | 1984 | 2.458744800078 | | 1983 | 2.5724124930108 | | 1982 | 2.6298899191044 | | 1981 | 2.6567608259322 | | 1980 | 2.6299287407218 | | 1979 | 2.5778651458097 | | 1978 | 2.5668749326241 | | 1977 | 2.5024588117324 | | 1976 | 2.4583243229994 | | 1975 | 2.471468601299 | | 1974 | 2.4733714148461 | | 1973 | 2.5055216144243 | | 1972 | 2.5451881395441 | | 1971 | 2.6038789787654 | | 1970 | 2.635983017697 | | 1969 | 2.6351115924886 | | 1968 | 2.6597668186094 | | 1967 | 2.6664146036735 | | 1966 | 2.6300703054352 | | 1965 | 2.5553822759036 | | 1964 | 2.464668154362 | | 1963 | 2.562102067185 | | 1962 | 2.6387040987343 | | 1961 | 2.6158267360655 |
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