| Year | Value | | 2021 | 41.875 | | 2020 | 41.875 | | 2019 | 41.875 | | 2018 | 41.875 | | 2017 | 41.875 | | 2016 | 41.875 | | 2015 | 41.875 | | 2014 | 41.87375 | | 2013 | 41.873125 | | 2012 | 41.871875 | | 2011 | 41.87125 | | 2010 | 41.87 | | 2009 | 41.870625 | | 2008 | 41.87125 | | 2007 | 41.87125 | | 2006 | 41.871875 | | 2005 | 41.8725 | | 2004 | 41.873125 | | 2003 | 41.87375 | | 2002 | 41.87375 | | 2001 | 41.874375 | | 2000 | 41.875 | | 1999 | 41.75 | | 1998 | 41.625 | | 1997 | 41.5 | | 1996 | 41.375 | | 1995 | 41.25 | | 1994 | 41.125 | | 1993 | 41 | | 1992 | 40.875 | | 1991 | 40.75 | | 1990 | 40.625 |
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