| Year | Value | | 2021 | 36.399936112442 | | 2020 | 35.921430852763 | | 2019 | 35.322580645161 | | 2018 | 33.769758901485 | | 2017 | 33.583435768905 | | 2016 | 34.207081510807 | | 2015 | 34.667198723065 | | 2014 | 37.51316839585 | | 2013 | 36.545672118069 | | 2012 | 36.067587835466 | | 2011 | 34.874110476434 | | 2010 | 33.943358595931 | | 2009 | 32.767451136817 | | 2008 | 29.700837654567 | | 2007 | 29.285258455648 | | 2006 | 29.974473516273 | | 2005 | 30.416400765794 | | 2004 | 25.788130185067 | | 2003 | 24.32992980217 | | 2002 | 26.148691767709 | | 2001 | 26.021059349075 | | 2000 | 45.915762603701 | | 1999 | 47.112316528398 | | 1998 | 46.107211231653 | | 1997 | 45.915762603701 | | 1996 | 45.72431397575 | | 1995 | 45.72431397575 | | 1994 | 41.320995532865 | | 1993 | 45.118059987237 | | 1992 | 46.027440970006 |
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