| Year | Value | | 2022 | 52.897820682748 | | 2021 | 48.740048488607 | | 2020 | 48.812768833659 | | 2019 | 50.045956004927 | | 2018 | 48.098613136603 | | 2017 | 48.400492221962 | | 2016 | 48.650638267332 | | 2015 | 48.603401845333 | | 2014 | 48.295026521716 | | 2013 | 47.457079172589 | | 2012 | 46.532961317153 | | 2011 | 46.005328507366 | | 2010 | 46.250150794644 | | 2009 | 47.58627647951 | | 2008 | 49.562927931021 | | 2007 | 54.274719213597 | | 2006 | 50.15181818082 | | 2005 | 51.056691833109 | | 2004 | 49.620515730575 | | 2003 | 50.333493342689 | | 2002 | 50.155840488855 | | 2001 | 50.560852681888 | | 2000 | 50.919978193151 | | 1999 | 51.185437810151 | | 1998 | 51.652463115347 | | 1997 | 51.162333309832 | | 1996 | 51.034824726811 | | 1995 | 51.005334542998 | | 1994 | 50.482990913038 | | 1993 | 50.909264181219 | | 1992 | 50.792008007247 | | 1991 | 50.825878718911 |
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