Year | Value | 2018 | 1,215.272 | 2017 | 1,181 | 2016 | 1,128 | 2015 | 997 | 2014 | 953 | 2013 | 492 | 2009 | 16,840 | 2008 | 22,894 | 2007 | 22,401 | 2006 | 21,133 | 2005 | 21,787 | 2004 | 23,338 | 2003 | 23,976 | 2002 | 23,343 | 2001 | 24,440 | 2000 | 16,577 | 1999 | 20,600 | 1998 | 12,500 | 1997 | 12,300 | 1996 | 18,300 | 1995 | 17,000 | 1994 | 18,700 | 1993 | 20,000 | 1992 | 20,000 | 1991 | 20,900 | 1990 | 21,300 | 1989 | 25,200 | 1988 | 23,300 | 1987 | 24,000 | 1986 | 21,600 | 1985 | 27,700 | 1984 | 26,500 | 1983 | 29,200 | 1982 | 20,000 | 1981 | 19,500 | 1980 | 20,700 | 1979 | 21,100 | 1978 | 20,100 | 1977 | 19,800 | 1976 | 23,800 | 1975 | 12,600 | 1974 | 16,100 | 1973 | 13,700 | 1972 | 21,500 | 1971 | 19,500 | 1970 | 18,600 |
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