| Year | Value | | 2020 | 0.79643620550206 | | 2019 | 0.79763543932944 | | 2018 | 0.80584040910739 | | 2017 | 0.80729850387102 | | 2016 | 0.81773847224461 | | 2015 | 0.82338079319052 | | 2014 | 0.82850351440758 | | 2013 | 0.83385158376621 | | 2012 | 0.87182323943473 | | 2011 | 0.87756573877828 | | 2010 | 0.89112558738647 | | 2009 | 0.89311349109543 | | 2008 | 0.89019629079738 | | 2007 | 0.89352598523914 | | 2006 | 0.95883818474869 | | 2005 | 0.96517706200405 | | 2004 | 0.9438954790544 | | 2003 | 0.9812659880058 | | 2002 | 0.99767838255514 | | 2001 | 1.0097421532474 | | 2000 | 1.0630815970599 | | 1999 | 1.0884702984677 | | 1998 | 1.1241767064023 | | 1997 | 1.1433111670311 | | 1996 | 1.179313410057 | | 1995 | 1.2002896821636 | | 1994 | 0.93671465994093 | | 1993 | 0.97571804839173 | | 1992 | 1.0334444089342 | | 1991 | 1.0325727856497 |
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