| Year | Value | | 2021 | 7,583 | | 2020 | 6,779 | | 2019 | 12,178 | | 2018 | 10,479 | | 2017 | 11,955 | | 2016 | 15,911 | | 2015 | 18,924 | | 2014 | 19,763.599680779 | | 2013 | 19,596 | | 2012 | 13,263.251468488 | | 2011 | 12,957 | | 2010 | 13,705 | | 2009 | 11,260 | | 2008 | 10,943 | | 2007 | 10,791 | | 2006 | 10,490 | | 2005 | 9,768 | | 2004 | 8,585 | | 2003 | 7,662 | | 2002 | 7,501 | | 2001 | 7,257 | | 2000 | 6,698 | | 1999 | 5,900 | | 1998 | 5,000 | | 1997 | 4,600 | | 1996 | 3,800 | | 1995 | 3,200 | | 1994 | 3,800 | | 1993 | 3,700 | | 1992 | 4,400 | | 1991 | 5,100 | | 1990 | 5,600 | | 1989 | 4,900 | | 1988 | 4,700 | | 1987 | 3,300 | | 1986 | 2,900 | | 1985 | 2,500 | | 1984 | 4,500 | | 1983 | 6,200 | | 1982 | 5,500 | | 1981 | 5,400 | | 1980 | 6,100 | | 1979 | 5,500 | | 1978 | 5,300 | | 1977 | 4,300 | | 1976 | 8,000 | | 1975 | 4,600 |
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