| Year | Value | | 2021 | 6.1675600982767 | | 2020 | -9.4330044547561 | | 2019 | 0.39205892185976 | | 2018 | 1.46570337693 | | 2017 | 1.739282982802 | | 2016 | 3.8930795878462 | | 2015 | 0.6685459666125 | | 2014 | 1.0619724892303 | | 2013 | -1.5374032447199 | | 2012 | -3.893582215022 | | 2011 | 0.31074396799443 | | 2010 | 0.22951495880636 | | 2009 | -4.0313885376342 | | 2008 | -3.3945224226581 | | 2007 | 1.2816166443693 | | 2006 | 1.094799178894 | | 2005 | 0.17515542584657 | | 2004 | 1.3766867307755 | | 2003 | 0.16575134891923 | | 2002 | 0.064204734792668 | | 2001 | 2.357157375883 | | 2000 | 2.0418673912309 | | 1999 | 1.8944552177852 | | 1998 | 2.2851449775338 | | 1997 | 2.458022010093 | | 1996 | 2.08371313206 | | 1995 | 2.9307271434023 | | 1994 | 1.6904626756543 | | 1993 | -1.5891570051646 | | 1992 | 0.14818526284424 | | 1991 | 2.0120925654058 | | 1990 | 2.1034474657427 | | 1989 | 3.010278413427 | | 1988 | 4.14676370811 | | 1987 | 4.0236159817684 | | 1986 | 5.631728501553 | | 1985 | 2.6516985454021 | | 1984 | 3.0869147894372 | | 1983 | 1.9392310263314 | | 1982 | 1.2325198389066 | | 1981 | -1.4351660617436 | | 1980 | 1.154351697953 | | 1979 | 6.2395877928444 | | 1978 | 3.9124969809467 | | 1977 | 3.2482109359523 | | 1976 | 6.0061771460358 | | 1975 | -1.989292673893 | | 1974 | 0.99467407785159 | | 1973 | 4.0512739618049 | | 1972 | 3.9149768739248 | | 1971 | 2.1165592107907 |
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