Year | Value | 2021 | 8,802 | 2020 | 8,477 | 2019 | 18,704 | 2018 | 18,671 | 2017 | 20,539 | 2016 | 19,178 | 2015 | 17,124 | 2014 | 14,556 | 2013 | 14,592 | 2012 | 11,262 | 2011 | 14,202 | 2010 | 12,989 | 2009 | 11,238 | 2008 | 11,896 | 2007 | 20,727 | 2006 | 19,526 | 2005 | 19,581 | 2004 | 19,281 | 2003 | 18,647 | 2002 | 22,449 | 2001 | 20,249 | 2000 | 18,966 | 1999 | 18,500 | 1998 | 18,900 | 1997 | 17,900 | 1996 | 17,200 | 1995 | 14,000 | 1994 | 13,400 | 1993 | 13,600 | 1992 | 6,000 | 1991 | 16,300 | 1990 | 15,800 | 1989 | 14,900 | 1988 | 14,700 | 1987 | 14,800 | 1986 | 16,200 | 1985 | 12,500 | 1984 | 9,800 | 1983 | 6,200 | 1982 | 6,200 | 1981 | 2,000 | 1980 | 2,000 | 1979 | 2,000 | 1978 | 2,000 | 1977 | 2,000 | 1976 | 2,000 |
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