| Year | Value | | 2020 | 0.99418000809635 | | 2019 | 0.97796223232104 | | 2018 | 0.98148578936796 | | 2017 | 0.98254448316625 | | 2016 | 0.98618962955807 | | 2015 | 0.89772962105924 | | 2014 | 0.88758030788789 | | 2013 | 0.89142223805566 | | 2012 | 0.90556457367049 | | 2011 | 0.91048906038499 | | 2010 | 0.93844660262997 | | 2009 | 0.9128474383542 | | 2008 | 0.7247578176455 | | 2007 | 0.71377927089827 | | 2006 | 0.7139295994022 | | 2005 | 3.2528008833424 | | 2004 | 3.2306685604258 | | 2003 | 3.1804299871443 | | 2002 | 3.6061964012767 | | 2001 | 5.7202517371843 | | 2000 | 3.8881607939298 | | 1999 | 4.1797170043823 | | 1998 | 4.3679438836876 | | 1997 | 4.3474237087123 | | 1996 | 4.2998857515544 | | 1995 | 4.6211084367675 | | 1994 | 3.5825828052009 | | 1993 | 2.7578097034086 | | 1992 | 3.8046783658212 | | 1991 | 4.7264451035986 |
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