| Year | Value | | 2022 | 36.002945258505 | | 2021 | 35.514286970076 | | 2020 | 35.163585069819 | | 2019 | 34.809537923774 | | 2018 | 34.09762488263 | | 2017 | 33.404649607855 | | 2016 | 32.586039693249 | | 2015 | 31.650579970718 | | 2014 | 30.624754248398 | | 2013 | 28.416593371593 | | 2012 | 26.36084594253 | | 2011 | 24.248593233219 | | 2010 | 22.227393440963 | | 2009 | 20.37971136781 | | 2008 | 18.657090076344 | | 2007 | 16.962583299656 | | 2006 | 15.541622491517 | | 2005 | 14.138915229751 | | 2004 | 12.783841838035 | | 2003 | 11.519711152592 | | 2002 | 10.390752799198 | | 2001 | 9.3080455919174 | | 2000 | 8.3692478391677 | | 1999 | 7.6296392477656 | | 1998 | 7.0444515498601 | | 1997 | 6.4703019584818 | | 1996 | 6.0731253529095 | | 1995 | 5.9251488787366 | | 1994 | 6.1540099651901 | | 1993 | 5.93586313686 | | 1992 | 5.893799966353 | | 1991 | 5.8594439494304 |
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