| Year | Value | | 2022 | -1.3553945932456 | | 2021 | -1.2168024899854 | | 2020 | 0.21459210657166 | | 2019 | 0.10533939272414 | | 2018 | 0.20288023825917 | | 2017 | 0.19778322475979 | | 2016 | 0.41591302827712 | | 2015 | 0.65886136087834 | | 2014 | 0.66611329003189 | | 2013 | 0.72512080665808 | | 2012 | 0.54075295054368 | | 2011 | 0.14795127740218 | | 2010 | 0.12888043266804 | | 2009 | 0.26302640134693 | | 2008 | 0.26545783672629 | | 2007 | 0.25475758193578 | | 2006 | 0.30033180096664 | | 2005 | 0.29324907405282 | | 2004 | 0.24741354282281 | | 2003 | 0.23864317532026 | | 2002 | 0.36656646214818 | | 2001 | 0.51988446396193 | | 2000 | 0.40904183823825 | | 1999 | 0.38347131161858 | | 1998 | 0.55421190292258 | | 1997 | 0.49326714482583 | | 1996 | 0.44067053086068 | | 1995 | 0.46719728919979 | | 1994 | 0.50070343787019 | | 1993 | 0.58826191924056 | | 1992 | 0.76388272245526 | | 1991 | 1.2003525367265 | | 1990 | 1.0578080119819 | | 1989 | 0.5218509800862 | | 1988 | 0.36319798730509 | | 1987 | 0.3343584944293 | | 1986 | 0.3307590735047 | | 1985 | 0.38828897916594 | | 1984 | 0.49815657620003 | | 1983 | 0.58172493232624 | | 1982 | 0.61646204011785 | | 1981 | 0.8966160628715 | | 1980 | 0.98222001605907 | | 1979 | 1.2466980667417 | | 1978 | 1.2966043585136 | | 1977 | 1.301109488896 | | 1976 | 1.5532135629487 | | 1975 | 0.93866035361126 | | 1974 | 0.36818331437502 | | 1973 | 0.454133111944 | | 1972 | 0.65003718800644 | | 1971 | 0.43384478780677 | | 1970 | 0.22819650825072 | | 1969 | 0.36542076251453 | | 1968 | 0.65053288974613 | | 1967 | 0.81441151725321 | | 1966 | 0.73780408125038 | | 1965 | 0.46778769631379 | | 1964 | 0.36261254676326 | | 1963 | 0.37089200518951 | | 1962 | 0.5957771033194 | | 1961 | 0.79290184696066 |
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