| Year | Value | | 2021 | 620 | | 2020 | 662 | | 2019 | 620 | | 2018 | 620 | | 2017 | 620 | | 2016 | 620 | | 2015 | 597 | | 2014 | 597 | | 2013 | 587 | | 2012 | 608 | | 2011 | 620.7 | | 2010 | 620.7 | | 2009 | 616 | | 2008 | 617 | | 2007 | 617 | | 2006 | 617 | | 2005 | 617 | | 2004 | 617 | | 2003 | 617 | | 2002 | 617 | | 2001 | 612 | | 2000 | 533 | | 1999 | 483 | | 1998 | 547 | | 1997 | 483 | | 1996 | 483 | | 1995 | 483 |
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