Year | Value | 2021 | 36,357 | 2020 | 32,964.6 | 2019 | 51,938 | 2018 | 51,824 | 2017 | 48,289 | 2016 | 48,255 | 2015 | 48,569 | 2014 | 47,215 | 2013 | 44,059 | 2012 | 43,021 | 2011 | 38,937 | 2010 | 38,716 | 2009 | 51,932 | 2008 | 47,639 | 2007 | 47,209 | 2006 | 43,777 | 2005 | 42,304 | 2004 | 42,447 | 2003 | 40,831 | 2002 | 25,102 | 2001 | 38,239 | 2000 | 34,007 | 1999 | 29,900 | 1998 | 24,600 | 1997 | 23,200 | 1996 | 8,200 | 1995 | 7,300 | 1994 | 18,900 | 1993 | 15,300 | 1992 | 15,200 | 1991 | 13,200 | 1990 | 12,300 | 1989 | 10,600 | 1988 | 10,400 | 1987 | 10,300 | 1986 | 9,200 | 1985 | 7,900 | 1984 | 7,500 | 1983 | 6,900 | 1982 | 7,300 | 1981 | 6,200 | 1980 | 6,000 | 1979 | 8,600 | 1978 | 8,600 | 1977 | 8,300 | 1976 | 8,200 | 1975 | 8,000 | 1974 | 7,900 | 1973 | 7,500 | 1972 | 8,200 | 1971 | 9,100 | 1970 | 7,100 |
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