| Year | Value | | 2020 | 0.84851603954686 | | 2019 | 0.83970064414478 | | 2018 | 0.84966719633897 | | 2017 | 0.8552637988804 | | 2016 | 0.86805618922876 | | 2015 | 0.86320889158606 | | 2014 | 0.88008508585737 | | 2013 | 0.88588792651879 | | 2012 | 0.90158501928795 | | 2011 | 0.908544121393 | | 2010 | 0.93402050549931 | | 2009 | 0.96426195231037 | | 2008 | 0.97112947316892 | | 2007 | 0.99033561455122 | | 2006 | 1.0476826723952 | | 2005 | 1.0603533692661 | | 2004 | 1.0138791205997 | | 2003 | 1.0261069513655 | | 2002 | 1.0466067674029 | | 2001 | 1.0479533303219 | | 2000 | 1.123708450799 | | 1999 | 1.1362313199364 | | 1998 | 1.162109423447 | | 1997 | 1.1995405295308 | | 1996 | 1.2060267598739 | | 1995 | 1.1953564021908 | | 1994 | 0.85541548264031 | | 1993 | 0.88486919062281 | | 1992 | 0.90665754869238 | | 1991 | 0.95335823015108 |
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