| Year | Value | | 2021 | 3.3104006149594 | | 2020 | -7.6438990334723 | | 2019 | 6.6319929283218 | | 2018 | 27.998629906011 | | 2017 | 1.1465004589133 | | 2016 | 1.2142609646183 | | 2015 | 5.0585135561143 | | 2014 | 15.827286237189 | | 2013 | 12.728321181444 | | 2012 | 11.935635361996 | | 2011 | 15.423402396779 | | 2010 | 3.914249417018 | | 2009 | 3.9461445569812 | | 2008 | 6.9997520522713 | | 2007 | 0.42675821663226 | | 2006 | -2.4328687582518 | | 2005 | 12.24075366136 | | 2004 | -1.1261389081249 | | 2003 | 1.6450247765353 | | 2002 | 11.202868055566 | | 2001 | 27.215405670791 | | 2000 | -18.00089423955 | | 1999 | -2.3312946946408 | | 1998 | 10.019494649938 | | 1997 | 7.4875080962551 | | 1996 | 13.521196461009 | | 1995 | -5.0348000344334 | | 1994 | 25.562996534365 | | 1993 | -16.521357454413 | | 1992 | -17.795952498889 | | 1991 | 27.076218895501 | | 1990 | -13.159547264472 | | 1989 | -12.59664177517 | | 1988 | 37.119777579851 | | 1987 | -26.36841592387 | | 1986 | -18.378829710018 | | 1985 | -16.210593608032 | | 1984 | -2.6432381527926 | | 1983 | -5.8413544710514 | | 1982 | 4.1416053559621 | | 1981 | 44.638209423999 | | 1980 | 212.18984379684 | | 1979 | -51.655465241825 | | 1978 | -33.235917897451 | | 1977 | -21.306930508284 | | 1976 | 64.418766728097 | | 1975 | 33.073255133633 | | 1974 | 8.3802034731495 | | 1973 | 27.268897436381 | | 1972 | -8.3689389641716 | | 1971 | 14.865828619429 |
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