| Year | Value | | 2021 | 39.340795401458 | | 2020 | 36.209839695395 | | 2019 | 32.176339689793 | | 2018 | 27.754098457649 | | 2017 | 23.851860551488 | | 2016 | 21.166166521178 | | 2015 | 18.775959566585 | | 2014 | 16.389170792937 | | 2013 | 14.139757526079 | | 2012 | 12.070172743508 | | 2011 | 10.532032370845 | | 2010 | 9.3239548038468 | | 2009 | 7.9300002848137 | | 2008 | 6.9732724422041 | | 2007 | 6.2581904157943 | | 2006 | 5.5170552755286 | | 2005 | 4.5097045235396 | | 2004 | 3.5949226733622 | | 2003 | 2.8012499545251 | | 2002 | 1.4566722416569 | | 2001 | 0.73926374644698 | | 1999 | 0.07534209552965 | | 1998 | 0.043149920911517 | | 1997 | 0.025459214606193 | | 1996 | 0.0070921203860042 | | 1995 | 0.00080548425899938 | | 1994 | 7.9387912963975E-5 | | 1993 | 1.7091474773594E-5 |
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