| Year | Value | | 2021 | 77.373534539676 | | 2020 | 72.789257469893 | | 2019 | 67.333917299613 | | 2018 | 60.225838481738 | | 2017 | 54.883534826004 | | 2016 | 48.408764652092 | | 2015 | 44.354750500778 | | 2014 | 40.079562573797 | | 2013 | 35.152091465884 | | 2012 | 31.213209809802 | | 2011 | 27.770041989897 | | 2010 | 24.858150671089 | | 2009 | 21.653170045373 | | 2008 | 18.781885211107 | | 2007 | 15.074875627227 | | 2006 | 11.790598745931 | | 2005 | 9.7758140405618 | | 2004 | 8.4092748336308 | | 2003 | 5.1345094726917 | | 2002 | 3.7770551620142 | | 2001 | 2.1076205872312 | | 2000 | 1.7276123407684 | | 1999 | 0.9419800806014 | | 1998 | 0.49847832020052 | | 1997 | 0.23350027987625 | | 1996 | 0.085568255565581 | | 1995 | 0.031769878058161 | | 1994 | 0.013511151208632 | | 1993 | 0.0082559533003545 | | 1992 | 0.0058202434752507 | | 1991 | 0.0040208331450484 | | 1990 | 0.0020725407711205 |
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