| Year | Value | | 2021 | 6.7193324372947 | | 2020 | 0.7480807441985 | | 2019 | 0.48721979956625 | | 2018 | 2.398989160319 | | 2017 | 5.3855237638961 | | 2016 | 6.2994725779363 | | 2015 | 2.1246424108059 | | 2014 | 7.2611665386201 | | 2013 | 10.236331438194 | | 2012 | -2.2979467579725 | | 2011 | 5.3174993601175 | | 2010 | 11.496172332623 | | 2009 | 0.38073730220883 | | 2008 | 5.2847352211056 | | 2007 | 10.85138501279 | | 2006 | 5.3774503688234 | | 2005 | 0.73212649374813 | | 2004 | 4.8557608860002 | | 2003 | -4.1946911012782 | | 2002 | 13.578994404814 | | 2001 | 6.4472040049999 | | 2000 | -9.9317538848748 | | 1999 | -2.8804313821978 | | 1998 | 4.3644902664656 | | 1997 | -2.6348093224406 | | 1996 | 2.2877599042268 |
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