| Year | Value | | 2021 | 4.4898546553461 | | 2020 | 4.4610735357605 | | 2019 | 4.4179018563822 | | 2018 | 4.4754640955533 | | 2017 | 4.6625413728594 | | 2016 | 4.9503525687149 | | 2015 | 5.2914088358037 | | 2014 | 5.2525543243632 | | 2013 | 5.982155705857 | | 2012 | 5.3245071233271 | | 2011 | 5.4309972657936 | | 2010 | 5.6842711181465 | | 2009 | 6.231112390272 | | 2008 | 6.6052669448842 | | 2007 | 6.6628291840553 | | 2006 | 6.6484386242625 | | 2005 | 6.7635631026047 | | 2004 | 6.5045330263347 | | 2003 | 11.541228953806 | | 2002 | 11.498057274428 | | 2001 | 11.440495035257 | | 2000 | 11.411713915671 | | 1999 | 11.368542236293 | | 1998 | 11.397323355879 | | 1997 | 11.296589437329 | | 1996 | 11.239027198158 | | 1995 | 11.09512160023 | | 1994 | 11.440495035257 | | 1993 | 11.440495035257 | | 1992 | 11.440495035257 |
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