| Year | Value | | 2021 | -1.0722893378101 | | 2020 | 4.979408607061 | | 2019 | 5.021261961068 | | 2018 | 4.7873172282206 | | 2017 | 3.1579008883468 | | 2016 | 5.4767756468822 | | 2015 | 5.3962850392593 | | 2014 | 7.8513487857404 | | 2013 | 8.743884368336 | | 2012 | 4.945680563032 | | 2011 | 1.8486855985428 | | 2010 | 1.1453929041468 | | 2009 | 8.4865955446298 | | 2008 | 0.91594748478703 | | 2007 | 1.8512719496818 | | 2006 | 4.570565799491 | | 2005 | 1.4206111848062 | | 2004 | 9.5286118181701 | | 2003 | 8.6825315316369 | | 2002 | 3.7546380840314 | | 2001 | 4.2683938568731 | | 2000 | 0.95117217826454 | | 1999 | 6.4977696450598 | | 1998 | 7.2348208940052 | | 1997 | 9.5333672031949 | | 1996 | 1.8004666202274 | | 1995 | 0.89541679972041 | | 1994 | -1.0148982882293 | | 1993 | 19.161352169906 | | 1992 | -14.257278488448 | | 1991 | 1.9365547146948 | | 1990 | -5.4196295556647 | | 1989 | -18.17909488891 | | 1988 | -11.86745546921 | | 1987 | -8.9220739666499 | | 1986 | 24.307802818721 | | 1985 | 6.569384983556 | | 1984 | 6.9239693072426 | | 1983 | 0.73747258223092 | | 1982 | 32.005124754306 | | 1981 | 31.042443946131 | | 1980 | -15.042508968148 | | 1979 | 0.79232550442754 | | 1978 | 47.33406978174 | | 1977 | 2.2183508663919 | | 1976 | -7.1577086936433 | | 1975 | 11.332214202448 | | 1974 | 10.975669017387 | | 1973 | -5.874777776102 | | 1972 | 0.13674618666486 |
|