| Year | Value | | 2021 | 7.8635335538683 | | 2020 | 0.35434388063571 | | 2019 | 2.7643900186338 | | 2018 | 5.7832989987982 | | 2017 | 5.0700322843943 | | 2016 | 20.009245775425 | | 2015 | 5.3708107624395 | | 2014 | 5.4882268239001 | | 2013 | 4.2567246901287 | | 2012 | -1.6243507904643 | | 2011 | 6.9527213598997 | | 2010 | 3.3036345717278 | | 2009 | 11.159925166438 | | 2008 | 1.8902111552696 | | 2007 | 1.9828911514416 | | 2006 | 6.947914547722 | | 2005 | 8.4628180077848 | | 2004 | 7.562705683781 | | 2003 | 5.7697057592695 | | 2002 | 1.9934358707343 | | 2001 | 2.0037517591686 | | 2000 | -16.915065317283 | | 1999 | 3.5882313717937 | | 1998 | 5.6784842639899 | | 1997 | 0.66756375264754 | | 1996 | 4.5034978807942 | | 1995 | 6.4184918584604 | | 1994 | 4.010489035625 | | 1993 | 1.5024346522299 | | 1992 | 6.94207302495 | | 1991 | 3.8769215262175 | | 1990 | 3.212993306787 | | 1989 | 3.3403068381795 | | 1988 | 7.3655386340005 | | 1987 | 7.0405910643466 |
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