| Year | Value | | 2022 | 0.14136847010652 | | 2021 | 0.21399450973283 | | 2020 | 0.54502623730847 | | 2019 | 0.89056318303305 | | 2018 | 0.84131423757162 | | 2017 | 0.79323421565164 | | 2016 | 0.7423534047846 | | 2015 | 0.66170310123715 | | 2014 | 0.548094105535 | | 2013 | 0.41722548562677 | | 2012 | 0.30702071237862 | | 2011 | -2.9399811793577 | | 2010 | -5.3439380452557 | | 2009 | -5.084451170303 | | 2008 | -4.9050309027169 | | 2007 | -4.6635357551715 | | 2006 | -4.3905337853575 | | 2005 | -4.0779690112216 | | 2004 | -3.7200322755171 | | 2003 | -3.3458337183891 | | 2002 | -2.9585727955389 | | 2001 | -1.0749898598734 | | 2000 | 5.2395825272756 | | 1999 | 10.699856544709 | | 1998 | 11.897898854876 | | 1997 | 13.067677774177 | | 1996 | 9.1164532260182 | | 1995 | 1.9420903253397 | | 1994 | 0.35099484471898 | | 1993 | 0.37470379825212 | | 1992 | 0.36088393413651 | | 1991 | 0.62302909622136 | | 1990 | 4.5671205009496 | | 1989 | 7.8871323099394 | | 1988 | 8.5114813058246 | | 1987 | 9.3208236080601 | | 1986 | 10.136076675942 | | 1985 | 10.890044073967 | | 1984 | 11.57579429443 | | 1983 | 12.233055618981 | | 1982 | 12.920716363263 | | 1981 | 12.218296344281 | | 1980 | 6.5640587338995 | | 1979 | 1.8355875147241 | | 1978 | 1.8258802933663 | | 1977 | 1.9431650270493 | | 1976 | 2.1125720858392 | | 1975 | 2.412790207134 | | 1974 | 5.5947552225204 | | 1973 | 10.178776233552 | | 1972 | 12.101882291153 | | 1971 | 10.615877726392 | | 1970 | 1.9010276397035 | | 1969 | -4.7871046457669 | | 1968 | -2.6466573188163 | | 1967 | 1.342932329674 | | 1966 | 3.3455008871046 | | 1965 | 3.3702677840249 | | 1964 | 3.3831821531312 | | 1963 | 3.2852579734116 | | 1962 | 3.1511637312097 | | 1961 | 2.9775222758608 |
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