| Year | Value | | 2020 | 0.97049091435649 | | 2019 | 0.97229679498567 | | 2018 | 0.98361331443963 | | 2017 | 0.99549247328683 | | 2016 | 1.0089437256032 | | 2015 | 1.0234160849169 | | 2014 | 1.0385075295093 | | 2013 | 1.0546259409189 | | 2012 | 0.86748975001327 | | 2011 | 0.88191991544636 | | 2010 | 0.89708263450303 | | 2009 | 0.96246190962634 | | 2008 | 1.1190053402884 | | 2007 | 1.3530963221515 | | 2006 | 1.64668792939 | | 2005 | 1.9091013223708 | | 2004 | 2.0336313823487 | | 2003 | 2.1862228994944 | | 2002 | 1.9156663656993 | | 2001 | 3.2547010705008 | | 2000 | 3.4824673597832 | | 1999 | 3.7005482461096 | | 1998 | 3.9636865795019 | | 1997 | 4.2419532413704 | | 1996 | 4.5280650161006 | | 1995 | 5.2244143505096 | | 1994 | 4.687675787842 | | 1993 | 4.5713411816335 | | 1992 | 4.889180066724 | | 1991 | 6.2778102236993 |
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