| Year | Value | | 2021 | 6.3427450392158 | | 2020 | -4.4973471142491 | | 2019 | 1.235909378147 | | 2018 | 0.70034477816267 | | 2017 | 2.4104797878697 | | 2016 | 0.21854548402396 | | 2015 | 4.0574127186425 | | 2014 | 1.7651823874938 | | 2013 | 1.6659693807947 | | 2012 | 1.6017403997017 | | 2011 | 2.3583344459607 | | 2010 | 3.3816685504034 | | 2009 | 5.7561060905343 | | 2008 | -3.8042360388365 | | 2007 | 3.3418158097592 | | 2006 | 6.2441756121385 | | 2005 | 6.5975265166587 | | 2004 | 4.1716978456405 | | 2003 | 6.2518897879872 | | 2002 | 7.7867052001826 | | 2001 | 2.096992163873 | | 2000 | 4.5639778877004 | | 1999 | 1.2256206535413 | | 1998 | 1.1172493633841 | | 1997 | 3.0673727302578 | | 1996 | 3.8841320680069 | | 1995 | 5.4608156383937 | | 1994 | 2.4971527678255 | | 1993 | 5.3493593884361 | | 1992 | 2.0213115731708 | | 1991 | 2.2591982536125 | | 1990 | 0.31566459086783 | | 1989 | 2.9662668811621 | | 1988 | 4.1550708818436 | | 1987 | 6.812303536672 | | 1986 | -1.697029427674 | | 1985 | -6.7653213085011 | | 1984 | 8.0183221469853 | | 1983 | 1.925549218853 | | 1982 | 0.51166235002553 | | 1981 | 1.7979550449785 | | 1980 | 8.2594006264108 | | 1979 | 2.4161905214549 | | 1978 | 3.7272328197706 | | 1977 | -1.2384775267448 | | 1976 | -1.7689325927641 | | 1975 | -5.6270269979346 | | 1974 | 5.1309694922516 | | 1973 | 12.597873868499 | | 1972 | 3.7995463532693 |
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