| Year | Value | | 2021 | 65.796062389639 | | 2020 | 62.46654457718 | | 2019 | 54.688632018983 | | 2018 | 48.405892619721 | | 2017 | 44.574360424104 | | 2016 | 42.079113042158 | | 2015 | 39.176665840345 | | 2014 | 36.375270609532 | | 2013 | 34.007215719216 | | 2012 | 31.572684564294 | | 2011 | 28.577270286555 | | 2010 | 24.991151320072 | | 2009 | 20.714556391346 | | 2008 | 17.121954442993 | | 2007 | 13.752986590168 | | 2006 | 10.546427390259 | | 2005 | 8.7061854789498 | | 2004 | 7.4032872740097 | | 2003 | 5.7784266572696 | | 2002 | 4.4989581471111 | | 2001 | 2.6903123406636 | | 2000 | 1.8715310773314 | | 1999 | 0.97126919343045 | | 1998 | 0.49570409504283 | | 1997 | 0.21977282890947 | | 1996 | 0.11122144187709 | | 1995 | 0.050215210598968 | | 1994 | 0.018275925092131 | | 1993 | 0.0067392847024211 | | 1992 | 0.0023066285120113 | | 1991 | 0.00049348349017481 |
|