Year | Value | 2021 | 20,436 | 2020 | 17,004 | 2019 | 50,959 | 2018 | 46,450 | 2017 | 42,782 | 2016 | 33,387 | 2015 | 30,073 | 2014 | 26,610 | 2013 | 27,305 | 2012 | 28,814 | 2011 | 31,753 | 2010 | 41,848 | 2009 | 18,191 | 2008 | 17,999 | 2007 | 17,685 | 2006 | 20,673 | 2005 | 19,142 | 2004 | 19,512 | 2003 | 17,833 | 2002 | 18,929 | 2001 | 16,682 | 2000 | 17,486 | 1999 | 17,300 | 1998 | 18,700 | 1997 | 17,200 | 1996 | 19,400 | 1995 | 17,900 | 1994 | 17,200 | 1993 | 16,200 | 1992 | 14,300 | 1991 | 7,200 | 1990 | 10,000 | 1989 | 15,600 | 1988 | 15,000 | 1987 | 14,300 | 1986 | 14,300 | 1985 | 14,200 | 1984 | 14,700 | 1983 | 14,600 | 1982 | 13,300 | 1981 | 13,400 | 1980 | 12,900 | 1979 | 12,500 | 1978 | 12,500 | 1977 | 11,600 | 1976 | 9,700 | 1975 | 8,400 | 1974 | 7,600 | 1973 | 7,000 | 1972 | 6,800 | 1971 | 6,800 | 1970 | 6,700 |
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