| Year | Value | | 2021 | 4.8255560172411 | | 2020 | -6.6736648033494 | | 2019 | 1.1363909431046 | | 2018 | 0.40601190299566 | | 2017 | 3.3577180796134 | | 2016 | 0.55766690052613 | | 2015 | 0.74594515289678 | | 2014 | 1.2589036656758 | | 2013 | 3.4075062792784 | | 2012 | 1.0127399464107 | | 2011 | 4.2383275196469 | | 2010 | 6.4379506628807 | | 2009 | -2.2797252875065 | | 2008 | 2.8294730610037 | | 2007 | 6.5046743465735 | | 2006 | 8.021989785255 | | 2005 | 2.5701016301191 | | 2004 | 4.2869853750537 | | 2003 | 1.3692986571499 | | 2002 | 0.46789959715036 | | 2001 | 0.4203435302199 | | 2000 | 2.6372800760563 | | 1999 | 0.77080461433088 | | 1998 | 1.875907088712 | | 1997 | 5.5798531856829 | | 1996 | 3.034206405195 | | 1995 | 2.0359235176185 | | 1994 | 12.063527312031 | | 1993 | 2.5363269566361 | | 1992 | 3.7346467019697 | | 1991 | 5.9801567965475 | | 1990 | -2.336890935306 |
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