| Year | Value | | 2020 | 0.84895769219341 | | 2019 | 0.81145778390879 | | 2018 | 0.75853454424029 | | 2017 | 0.83977863435198 | | 2016 | 0.8274579553258 | | 2015 | 0.84840639540986 | | 2014 | 0.86980303893041 | | 2013 | 0.89170393590763 | | 2012 | 0.86697984743039 | | 2011 | 0.88860127398378 | | 2010 | 0.9106566626413 | | 2009 | 0.93301556716191 | | 2008 | 1.038572585838 | | 2007 | 1.0631963936378 | | 2006 | 1.0882695426003 | | 2005 | 1.1139020545923 | | 2004 | 0.56996295240809 | | 2003 | 1.0564558254735 | | 2002 | 1.2178265449652 | | 2001 | 1.2658708558553 | | 2000 | 1.3182785918148 | | 1999 | 1.2374791175399 | | 1998 | 1.2673111178388 | | 1997 | 1.298298507678 | | 1996 | 1.3300427091492 | | 1995 | 1.3626144028342 | | 1994 | 1.5462164084485 | | 1993 | 1.5615972016178 | | 1992 | 1.5590287251043 | | 1991 | 3.1400378374559 |
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