| Year | Value | | 2021 | 67.58 | | 2020 | 64.88490358 | | 2019 | 61.72995515 | | 2018 | 58.5961697 | | 2017 | 55.4032403 | | 2016 | 52.19132594 | | 2015 | 50.13931848 | | 2014 | 44.80327537 | | 2013 | 40.11682514 | | 2012 | 35.42 | | 2011 | 34.95 | | 2010 | 28.33 | | 2009 | 22.51 | | 2008 | 21.81 | | 2007 | 20.22 | | 2006 | 16.7 | | 2005 | 15.17222875 | | 2004 | 13.68908859 | | 2003 | 12.1871062 | | 2002 | 10.25262467 | | 2001 | 8.780904019 | | 2000 | 7.281535115 | | 1999 | 4.652213227 | | 1998 | 2.565279962 | | 1997 | 0.475629193 | | 1996 | 0.183769158 |
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