| Year | Value | | 2021 | 38.94501834 | | 2020 | 36.39474796 | | 2019 | 32.47362713 | | 2018 | 32.47362713 | | 2017 | 27.2 | | 2016 | 22.8 | | 2015 | 14.2 | | 2014 | 11.4 | | 2013 | 10.6 | | 2012 | 9.8 | | 2011 | 9 | | 2010 | 8.37 | | 2009 | 8.1 | | 2008 | 7.6 | | 2007 | 7.2 | | 2006 | 6.796000481 | | 2005 | 6.376201635 | | 2004 | 5.401261908 | | 2003 | 1.647358346 | | 2002 | 0.893432988 | | 2001 | 0.340832326 | | 2000 | 0.231270715 | | 1999 | 0.070658478 | | 1998 | 0.023999477 | | 1996 | 0.007484253 |
|