| Year | Value | | 2022 | 42.139205738979 | | 2021 | 42.227656874533 | | 2020 | 40.73277627099 | | 2019 | 40.274727196434 | | 2018 | 42.95711890686 | | 2017 | 49.401291569916 | | 2016 | 55.620327451395 | | 2015 | 39.405185815125 | | 2014 | 39.76121477073 | | 2013 | 39.746368449393 | | 2012 | 38.363159828683 | | 2011 | 36.971340842338 | | 2010 | 36.549923184666 | | 2009 | 36.938640344404 | | 2008 | 37.156524056927 | | 2007 | 38.493271915755 | | 2006 | 38.669037699897 | | 2005 | 41.337070593206 | | 2004 | 37.884743575426 | | 2003 | 39.852455075259 | | 2002 | 39.851344428262 | | 2001 | 35.575358688755 | | 2000 | 35.576843795298 | | 1999 | 35.247747966082 | | 1998 | 35.248089333817 | | 1997 | 36.433796227484 | | 1996 | 34.132528966946 | | 1995 | 34.132517843985 | | 1994 | 34.255986216654 | | 1993 | 34.131884739509 | | 1992 | 34.077629034545 | | 1991 | 34.126758291923 |
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