| Year | Value | | 2023 | 4,979 | | 2022 | 552 | | 2021 | 560 | | 2020 | 560 | | 2018 | 2,342 | | 2017 | 1,669 | | 2016 | 4,538 | | 2015 | 5,126 | | 2014 | 16,056 | | 2013 | 16,932 | | 2012 | 16,807.407295596 | | 2011 | 20,176.728526068 | | 2010 | 20,600 | | 2009 | 14,652 | | 2008 | 14,462 | | 2007 | 14,403 | | 2006 | 18,843 | | 2005 | 17,306 | | 2004 | 16,746 | | 2003 | 14,706 | | 2002 | 15,495 | | 2001 | 14,973 | | 2000 | 14,608 | | 1999 | 7,800 | | 1998 | 7,300 | | 1997 | 7,000 | | 1996 | 11,800 | | 1995 | 4,900 | | 1994 | 12,400 | | 1993 | 13,100 | | 1992 | 13,900 | | 1991 | 11,300 | | 1990 | 14,100 | | 1989 | 13,800 | | 1988 | 14,600 | | 1987 | 13,700 | | 1986 | 15,300 | | 1985 | 9,900 | | 1984 | 9,900 | | 1983 | 9,500 | | 1982 | 7,900 | | 1981 | 9,300 | | 1980 | 9,200 | | 1979 | 7,100 | | 1978 | 7,100 | | 1977 | 7,000 | | 1976 | 6,800 |
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