| Year | Value | | 2021 | 28.488517801404 | | 2020 | 24.511843904182 | | 2019 | 20.459006388263 | | 2018 | 18.54194198318 | | 2017 | 15.841365077914 | | 2016 | 13.465148594338 | | 2015 | 10.427505299849 | | 2014 | 7.8852559383024 | | 2013 | 6.0194609894188 | | 2012 | 4.9657287250307 | | 2011 | 3.9821889016264 | | 2010 | 3.3781829162216 | | 2009 | 2.71750272265 | | 2008 | 2.2101407919919 | | 2007 | 2.2501833114978 | | 2006 | 1.5005862887691 | | 2005 | 1.1793464289649 | | 2004 | 0.90096841415261 | | 2003 | 0.61021789524654 | | 2002 | 0.39787836601973 | | 2001 | 0.24174730526808 | | 2000 | 0.1663523626288 | | 1999 | 0.10255838788538 | | 1998 | 0.04476156679539 | | 1997 | 0.024481560832528 | | 1996 | 0.0089585611327217 | | 1995 | 0.0025304166513376 | | 1994 | 0.0002966136571842 |
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