| Year | Value | | 2022 | 47.177277163817 | | 2021 | 46.576221177123 | | 2020 | 45.925395734346 | | 2019 | 45.731772235931 | | 2018 | 44.519120247747 | | 2017 | 42.887303918649 | | 2016 | 41.395776261177 | | 2015 | 41.18750161423 | | 2014 | 42.073820480906 | | 2013 | 40.481797426479 | | 2012 | 36.939979558388 | | 2011 | 38.921558739465 | | 2010 | 43.298408171004 | | 2009 | 41.709790743291 | | 2008 | 39.82925985759 | | 2007 | 41.903989492251 | | 2006 | 40.764228302883 | | 2005 | 39.620671411229 | | 2004 | 39.27221677347 | | 2003 | 38.36240670661 | | 2002 | 37.400186258353 | | 2001 | 36.50603455761 | | 2000 | 35.561793501697 | | 1999 | 34.775491308072 | | 1998 | 34.072348767062 | | 1997 | 33.752630646102 | | 1996 | 33.568300390004 | | 1995 | 33.693035812349 | | 1994 | 33.366563918883 | | 1993 | 33.31432901055 | | 1992 | 33.447570609775 | | 1991 | 33.767352398115 |
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