| Year | Value | | 2022 | -2.2169668273665 | | 2021 | -1.5034295234994 | | 2020 | -1.0980316587629 | | 2019 | -1.6003165357823 | | 2018 | -1.7570044207485 | | 2017 | -1.727058466256 | | 2016 | -1.1630223779771 | | 2015 | 0.76704955967386 | | 2014 | 0.060972060210101 | | 2013 | 0.026783769475635 | | 2012 | 0.01310954353923 | | 2011 | 0.057836264879371 | | 2010 | 0.099832974016897 | | 2009 | 0.12626339171085 | | 2008 | 0.19034915618877 | | 2007 | 0.23171832487194 | | 2006 | 0.27792276819599 | | 2005 | 0.24331871182595 | | 2004 | 0.2474471540591 | | 2003 | 0.28160249532047 | | 2002 | 0.2315800620514 | | 2001 | 0.22362563730256 | | 2000 | 0.20337172205468 | | 1999 | 0.15701055196042 | | 1998 | 0.040397572607627 | | 1997 | 0.36983535211378 | | 1996 | 0.20022062472902 | | 1995 | 0.48591625280187 | | 1994 | 0.24340337696812 | | 1993 | 0.027023220976101 | | 1992 | 0.081057946746518 | | 1991 | 0.24353509518055 | | 1990 | 0.46165404943267 | | 1989 | 0.71019740048883 | | 1988 | 0.90869357697888 | | 1987 | 1.0287834060005 | | 1986 | 0.98301714740407 | | 1985 | 0.96429440906773 | | 1984 | 0.97364784821862 | | 1983 | 0.95418456296635 | | 1982 | 0.9340315311882 | | 1981 | 0.88365407717194 | | 1980 | 0.86170708208035 | | 1979 | 0.89928257686574 | | 1978 | 0.93784988034817 | | 1977 | 0.97739603248886 | | 1976 | 1.049053507109 | | 1975 | 1.0602144284366 | | 1974 | 1.0715361032977 | | 1973 | 1.0511395893548 | | 1972 | 1.0623060123163 | | 1971 | 1.0737122303104 | | 1970 | 1.1184168345787 | | 1969 | 1.1980372125675 | | 1968 | 1.2803128686866 | | 1967 | 1.4000833397243 | | 1966 | 1.524627291903 | | 1965 | 1.6191734780268 | | 1964 | 1.8625336057377 | | 1963 | 2.0453172349285 | | 1962 | 2.314429301114 | | 1961 | 2.5627617920796 |
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