Year | Value | 2021 | 21.424705484159 | 2020 | 20.691074911318 | 2019 | 21.292953558877 | 2018 | 20.959212986986 | 2017 | 20.941809328623 | 2016 | 21.774690073667 | 2015 | 21.640064286594 | 2014 | 20.747371862229 | 2013 | 20.167223104024 | 2012 | 19.952075947991 | 2011 | 19.243873212716 | 2010 | 19.82395754239 | 2009 | 21.521023140909 | 2008 | 19.302067918381 | 2007 | 20.222989178807 | 2006 | 19.959274607504 | 2005 | 19.100312343795 | 2004 | 20.232659630687 | 2003 | 19.829203197557 | 2002 | 19.634315021387 | 2001 | 19.221078251839 | 2000 | 19.686161469106 | 1999 | 20.92459031917 | 1998 | 22.107347398681 | 1997 | 21.967189168078 | 1996 | 21.849091161069 | 1995 | 22.839017373966 |
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