| Year | Value | | 2021 | 57.038596491228 | | 2020 | 57.038596491228 | | 2019 | 57.038596491228 | | 2018 | 57.038596491228 | | 2017 | 57.038596491228 | | 2016 | 55.699332873246 | | 2015 | 55.693811824247 | | 2014 | 55.30278352887 | | 2013 | 54.911755233494 | | 2012 | 55.909790044822 | | 2011 | 55.508799245105 | | 2010 | 55.107808445388 | | 2009 | 54.878674215617 | | 2008 | 54.649539985846 | | 2007 | 54.420405756075 | | 2006 | 54.191271526303 | | 2005 | 53.962137296532 | | 2004 | 53.733003066761 | | 2003 | 53.50386883699 | | 2002 | 53.274734607219 | | 2001 | 53.045600377447 | | 2000 | 52.816466147676 | | 1999 | 52.73864118896 | | 1998 | 52.660816230243 | | 1997 | 52.582991271526 | | 1996 | 52.50516631281 | | 1995 | 52.427341354093 | | 1994 | 52.349516395376 | | 1993 | 52.27169143666 | | 1992 | 52.193866477943 |
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