| Year | Value | | 2021 | 19.73016812 | | 2020 | 13.71677775 | | 2019 | 11.83136182 | | 2018 | 8.7 | | 2017 | 6.4 | | 2016 | 4.713662899 | | 2015 | 4.17397219 | | 2014 | 3.7 | | 2013 | 3 | | 2012 | 2.3 | | 2011 | 1.9 | | 2010 | 1.7 | | 2009 | 1.63 | | 2008 | 1.65 | | 2007 | 0.65 | | 2006 | 0.607552239 | | 2005 | 0.567721802 | | 2004 | 0.525353655 | | 2003 | 0.423252419 | | 2002 | 0.339720155 | | 2001 | 0.222511586 | | 2000 | 0.196394691 | | 1999 | 0.168608781 | | 1998 | 0.062561023 | | 1997 | 0.014333647 | | 1996 | 0.003695196 |
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