| Year | Value | | 2022 | 38.596259650093 | | 2021 | 38.26366396052 | | 2020 | 38.040080517306 | | 2019 | 38.070007789303 | | 2018 | 37.849864142358 | | 2017 | 37.782922747855 | | 2016 | 37.786356730162 | | 2015 | 37.845197321095 | | 2014 | 37.793477132057 | | 2013 | 37.592732796364 | | 2012 | 37.391548962901 | | 2011 | 37.357672037035 | | 2010 | 36.948824515317 | | 2009 | 36.571990631441 | | 2008 | 36.271380904738 | | 2007 | 35.710966820659 | | 2006 | 35.374717596597 | | 2005 | 35.151756691823 | | 2004 | 35.19635763202 | | 2003 | 35.20195015107 | | 2002 | 35.295561050008 | | 2001 | 35.444181462932 | | 2000 | 35.609358969778 | | 1999 | 35.265909667824 | | 1998 | 34.864868898474 | | 1997 | 34.417322662727 | | 1996 | 34.213643557266 | | 1995 | 33.801200148131 | | 1994 | 33.522621314851 | | 1993 | 34.238016984835 | | 1992 | 34.109680091705 | | 1991 | 34.188313148289 |
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