| Year | Value | | 2020 | 1.1586142973004 | | 2019 | 1.146177783636 | | 2018 | 0.87859050653671 | | 2017 | 1.1994146856334 | | 2016 | 0.92262270882027 | | 2015 | 0.95650454977331 | | 2014 | 0.69506503822858 | | 2013 | 0.72798369316527 | | 2012 | 0.7555206976694 | | 2011 | 0.78454227562091 | | 2010 | 0.81551497829177 | | 2009 | 0.84832032575501 | | 2008 | 0.84054803732033 | | 2007 | 0.87459987055922 | | 2006 | 0.91018312884552 | | 2005 | 0.94724777159962 | | 2004 | 0.98583357157645 | | 2003 | 1.1288882503258 | | 2002 | 1.1758417958311 | | 2001 | 1.225613085091 | | 2000 | 1.2792631444288 | | 1999 | 1.2775121363653 | | 1998 | 1.3481068727772 | | 1997 | 1.4055848571658 | | 1996 | 1.5637883483552 | | 1995 | 1.6538866335889 | | 1994 | 1.5808277213949 | | 1993 | 1.6233502702878 | | 1992 | 1.6698393614534 | | 1991 | 1.7217630853995 |
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