| Year | Value | | 2021 | 3.8418706263105 | | 2020 | -10.081067321689 | | 2019 | 5.9471007737196 | | 2018 | 2.9553943602006 | | 2017 | 2.5336672879358 | | 2016 | 1.6151220363211 | | 2015 | 2.5953253960478 | | 2014 | 2.6390152051064 | | 2013 | 6.1795451218933 | | 2012 | 7.3259497787771 | | 2011 | 8.5065399392994 | | 2010 | 11.800874702011 | | 2009 | 3.4996643818368 | | 2008 | 9.6893182658608 | | 2007 | 11.167592725539 | | 2006 | 8.032387271566 | | 2005 | 5.7875469150802 | | 2004 | 2.7194724749468 | | 2003 | 3.1268405494409 | | 2002 | 5.4251252312701 | | 2001 | 1.2330226693187 | | 2000 | 0.81805124759346 | | 1999 | -1.8526626876286 | | 1998 | -1.5274494787006 | | 1997 | 7.4517071047109 | | 1996 | 3.2754987598281 | | 1995 | 7.8511251567451 | | 1994 | 12.933799922328 | | 1993 | 4.66841472493 | | 1992 | 0.10807060379849 | | 1991 | 8.1730649358136 | | 1990 | 5.1920837861118 | | 1989 | -11.254976441951 | | 1988 | 38.556770181227 | | 1987 | -8.5160602805974 | | 1986 | -30.829817191897 | | 1985 | 33.670446088139 | | 1984 | -27.258590579382 | | 1983 | -25.438656513911 |
|