| Year | Value | | 2022 | 57.708811319741 | | 2021 | 57.311432293687 | | 2020 | 57.267679885115 | | 2019 | 56.627643533378 | | 2018 | 51.109110950229 | | 2017 | 51.468429331448 | | 2016 | 51.690018609591 | | 2015 | 49.282034390942 | | 2014 | 49.72022470009 | | 2013 | 49.24661721429 | | 2012 | 47.621093804037 | | 2011 | 43.882417860507 | | 2010 | 43.073291095795 | | 2009 | 37.786776418091 | | 2008 | 36.87945776691 | | 2007 | 37.46354645526 | | 2006 | 37.516028594621 | | 2005 | 38.1324040838 | | 2004 | 38.778306774268 | | 2003 | 39.480795303793 | | 2002 | 40.182092990541 | | 2001 | 40.931927846284 | | 2000 | 41.722282737914 | | 1999 | 41.919116516011 | | 1998 | 42.106574710628 | | 1997 | 42.375561384939 | | 1996 | 42.422372135304 | | 1995 | 42.621922419275 | | 1994 | 42.683104583672 | | 1993 | 42.748792443014 | | 1992 | 42.894478543665 | | 1991 | 42.98515467196 |
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