| Year | Value | | 2021 | 15,982 | | 2020 | 12,838 | | 2019 | 27,711 | | 2018 | 27,189 | | 2017 | 26,809 | | 2016 | 26,171 | | 2015 | 25,183 | | 2014 | 25,161 | | 2013 | 24,305 | | 2012 | 26,456 | | 2011 | 26,743 | | 2010 | 24,766 | | 2009 | 24,613 | | 2008 | 24,728 | | 2007 | 22,391 | | 2006 | 21,641 | | 2005 | 22,031 | | 2004 | 20,482 | | 2003 | 19,751 | | 2002 | 19,340 | | 2001 | 18,258 | | 2000 | 16,955 | | 1999 | 15,900 | | 1998 | 16,800 | | 1997 | 16,700 | | 1996 | 15,000 | | 1995 | 13,300 | | 1994 | 12,000 | | 1993 | 9,200 | | 1992 | 4,100 | | 1991 | 1,900 |
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