| Year | Value | | 2022 | 0.013099501352578 | | 2021 | 0.089252200041253 | | 2020 | 0.23804087022988 | | 2019 | 0.35474089017083 | | 2018 | 0.46767205346196 | | 2017 | 0.60524501348297 | | 2016 | 0.57305090606965 | | 2015 | 0.58145614665765 | | 2014 | 0.63032638954189 | | 2013 | 0.66607297769007 | | 2012 | 0.6783454588468 | | 2011 | 0.54645759488027 | | 2010 | 0.48295968867836 | | 2009 | 0.49738140088493 | | 2008 | 0.51238693163744 | | 2007 | 0.52227186639227 | | 2006 | 0.558374367373 | | 2005 | 0.58812498955699 | | 2004 | 0.59393281511214 | | 2003 | 0.62286093613358 | | 2002 | 0.66999956775863 | | 2001 | 0.72638063783853 | | 2000 | 0.78795659295399 | | 1999 | 0.86585139299328 | | 1998 | 0.95955040629815 | | 1997 | 1.0234500241988 | | 1996 | 1.0481415141216 | | 1995 | 1.0865091508897 | | 1994 | 1.1302606321559 | | 1993 | 1.1496194308346 | | 1992 | 1.2255362283362 | | 1991 | 1.3644340084035 | | 1990 | 1.4673032108793 | | 1989 | 1.5331699959986 | | 1988 | 1.610071085787 | | 1987 | 1.6036050865576 | | 1986 | 1.487398929149 | | 1985 | 1.3616991182537 | | 1984 | 1.3120687611378 | | 1983 | 1.4449496950092 | | 1982 | 1.4726747601658 | | 1981 | 1.2809523442925 | | 1980 | 1.2542210519399 | | 1979 | 1.3339279535169 | | 1978 | 1.3381823383408 | | 1977 | 1.3627794757068 | | 1976 | 1.5473379728767 | | 1975 | 1.7663917816248 | | 1974 | 2.0659550133563 | | 1973 | 2.2833953639638 | | 1972 | 2.4573569295229 | | 1971 | 2.7469155496186 | | 1970 | 2.761675566453 | | 1969 | 2.7400021056956 | | 1968 | 2.6109026264853 | | 1967 | 2.5706976197388 | | 1966 | 2.7873318382169 | | 1965 | 2.3813681025195 | | 1964 | 2.3206829870686 | | 1963 | 2.4576474039515 | | 1962 | 0.82045554874852 | | 1961 | -1.0155277873132 |
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