| Year | Value | | 2022 | -1.1505139845943 | | 2021 | -1.4406525960419 | | 2020 | -1.2667710231153 | | 2019 | -1.1660813346502 | | 2018 | -1.1665948112876 | | 2017 | -1.1836266796693 | | 2016 | -1.2373057835376 | | 2015 | -1.3176065892299 | | 2014 | -1.29347782805 | | 2013 | -1.5583289022634 | | 2012 | -1.8542587666769 | | 2011 | -1.798934699136 | | 2010 | -1.7340375845377 | | 2009 | -1.6786178119057 | | 2008 | -1.6220158538438 | | 2007 | -1.245000870461 | | 2006 | 0.88835959110758 | | 2005 | -1.1791340790192 | | 2004 | 0.98232760960298 | | 2003 | 0.34962355023727 | | 2002 | 0.082875217024777 | | 2001 | 0.37213979616798 | | 2000 | 0.63213963525684 | | 1999 | 0.91811638851753 | | 1998 | 1.6492494731885 | | 1997 | 3.5198660387797 | | 1996 | 4.1065653253376 | | 1995 | 0.31420828882026 | | 1994 | -4.6898589887918 | | 1993 | -8.1017811826882 | | 1992 | -5.165263043559 | | 1991 | 0.17953262329218 | | 1990 | 0.29145899320527 | | 1989 | 0.40046785888365 | | 1988 | 0.51709419974355 | | 1987 | 0.60824654293059 | | 1986 | 0.68362421050332 | | 1985 | 0.77200370640355 | | 1984 | 0.8560545219902 | | 1983 | 0.89694533713402 | | 1982 | 0.8940852978392 | | 1981 | 0.8570678333035 | | 1980 | 0.82027100593247 | | 1979 | 0.81933371228901 | | 1978 | 0.85087636805315 | | 1977 | 0.89442768864909 | | 1976 | 0.93909114518322 | | 1975 | 0.97505467293879 | | 1974 | 1.0070717817208 | | 1973 | 1.0518070918842 | | 1972 | 1.0991541425533 | | 1971 | 1.1383086096543 | | 1970 | 1.1912973804738 | | 1969 | 1.262694026651 | | 1968 | 1.3439110799317 | | 1967 | 1.4400151442456 | | 1966 | 1.5399464336875 | | 1965 | 1.6274677519222 | | 1964 | 1.7085753627376 | | 1963 | 1.7852904608025 | | 1962 | 1.8525909165926 | | 1961 | 1.9064092868692 |
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