| Year | Value | | 2021 | 49.012205467125 | | 2020 | 45.394752708865 | | 2019 | 36.398656028619 | | 2018 | 29.807321214888 | | 2017 | 26.6973223611 | | 2016 | 23.809243792336 | | 2015 | 20.785482047399 | | 2014 | 18.518821876109 | | 2013 | 16.097739875694 | | 2012 | 14.239749303972 | | 2011 | 12.737350965615 | | 2010 | 10.530366532964 | | 2009 | 7.8885029484027 | | 2008 | 6.6910044712423 | | 2007 | 5.7240992759037 | | 2006 | 4.5847002111702 | | 2005 | 3.7839640185811 | | 2004 | 3.0929513716549 | | 2003 | 2.2036172023442 | | 2002 | 1.6185175663268 | | 2001 | 0.78513177993886 | | 2000 | 0.54291045259511 | | 1999 | 0.27242222322506 | | 1998 | 0.14860284187872 | | 1997 | 0.062639326827268 | | 1996 | 0.035496744158219 | | 1995 | 0.016411310788786 | | 1994 | 0.0013907126481699 | | 1993 | 0.00015334555661679 | | 1992 | 5.2396401529571E-5 |
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