| Year | Value | | 2021 | 34.845525076198 | | 2020 | 35.118869492934 | | 2019 | 35.39221390967 | | 2018 | 35.665558326406 | | 2017 | 35.938902743142 | | 2016 | 36.212247159878 | | 2015 | 36.485591576614 | | 2014 | 36.758880576337 | | 2013 | 37.03216957606 | | 2012 | 37.305458575783 | | 2011 | 37.578747575506 | | 2010 | 37.852036575229 | | 2009 | 38.125339429205 | | 2008 | 38.398642283181 | | 2007 | 38.671945137157 | | 2006 | 38.945247991133 | | 2005 | 39.218550845109 | | 2004 | 39.491853699086 | | 2003 | 39.765156553062 | | 2002 | 40.038459407038 | | 2001 | 40.311762261014 | | 2000 | 40.58506511499 | | 1999 | 40.858367968966 | | 1998 | 41.131670822943 | | 1997 | 41.404973676919 | | 1996 | 41.678276530895 | | 1995 | 41.951579384871 | | 1994 | 42.224882238847 | | 1993 | 42.498185092823 | | 1992 | 42.7714879468 | | 1991 | 43.044790800776 | | 1990 | 43.318093654752 |
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