| Year | Value | | 2020 | 0.10057754861263 | | 2019 | 0.10260562213581 | | 2018 | 0.10559842495424 | | 2017 | 0.10878029895546 | | 2016 | 0.1137778666634 | | 2015 | 0.11735104639945 | | 2014 | 0.12081518429059 | | 2013 | 0.12387387632982 | | 2012 | 0.12691875233504 | | 2011 | 0.12988768145686 | | 2010 | 0.13275191112503 | | 2009 | 0.13522948562751 | | 2008 | 0.13568784700653 | | 2007 | 0.13844098149712 | | 2005 | 0.14579729406471 | | 2004 | 0.15036104102467 | | 2003 | 0.15732415978374 | | 2002 | 0.16231648949212 | | 2001 | 0.16749747972322 | | 2000 | 0.21472443061177 | | 1999 | 0.22113299300508 | | 1998 | 0.22745124495824 | | 1997 | 0.23794023073593 | | 1996 | 0.24380544542171 | | 1995 | 0.24965949219259 | | 1994 | 0.35896352011689 | | 1993 | 0.34391420267716 | | 1992 | 0.3560637462473 | | 1991 | 0.31888708407657 |
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