| Year | Value | | 2022 | 34.734244706904 | | 2021 | 35.250161464456 | | 2020 | 30.376989812825 | | 2019 | 31.094763346749 | | 2018 | 31.38751683737 | | 2017 | 31.82193417636 | | 2016 | 33.653212792344 | | 2015 | 34.831800801277 | | 2014 | 33.420752410389 | | 2013 | 35.563644605403 | | 2012 | 36.230980384584 | | 2011 | 35.270826969829 | | 2010 | 39.354412429327 | | 2009 | 34.599570693122 | | 2008 | 28.750659014395 | | 2007 | 35.762438448897 | | 2006 | 40.593241818506 | | 2005 | 38.691297760766 | | 2004 | 36.61781485123 | | 2003 | 36.39187068425 | | 2002 | 32.577283475488 | | 2001 | 34.42705412061 | | 2000 | 37.555258930352 | | 1999 | 34.347131333095 | | 1998 | 34.237244334283 | | 1997 | 33.39080768579 | | 1996 | 32.10385688465 | | 1995 | 32.797064248619 |
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