| Year | Value | | 2021 | 58.827537759045 | | 2020 | 58.868984896382 | | 2019 | 58.904109589041 | | 2018 | 58.914646996839 | | 2017 | 58.872497365648 | | 2016 | 58.897084650509 | | 2015 | 58.893572181243 | | 2014 | 59.034070951879 | | 2013 | 59.114857744995 | | 2012 | 59.114857744995 | | 2011 | 59.645240604145 | | 2010 | 60.94134176326 | | 2009 | 61.338250790306 | | 2008 | 61.426062521953 | | 2007 | 61.534949069196 | | 2006 | 61.693010186161 | | 2005 | 56.375131717597 | | 2004 | 52.862662451703 | | 2003 | 50.720056199508 | | 2002 | 48.858447488585 | | 2001 | 46.645591851071 | | 2000 | 46.469968387777 | | 1999 | 46.469968387777 | | 1998 | 46.645591851071 | | 1997 | 46.786090621707 | | 1996 | 45.872848612575 | | 1995 | 43.69511766772 | | 1994 | 42.149631190727 | | 1993 | 41.482262030207 | | 1992 | 41.095890410959 |
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