Year | Value | 2021 | 45,832.196 | 2020 | 31,354 | 2019 | 49,931 | 2018 | 56,592 | 2017 | 54,102 | 2016 | 45,722 | 2015 | 42,682 | 2014 | 51,017.001872366 | 2013 | 33,467 | 2012 | 41,974.679204244 | 2011 | 40,751.450721649 | 2010 | 37,019 | 2009 | 19,011 | 2008 | 21,088 | 2007 | 24,089 | 2006 | 21,978 | 2005 | 25,644 | 2004 | 25,764 | 2003 | 28,901 | 2002 | 20,560 | 2001 | 20,007 | 2000 | 21,566 | 1999 | 24,000 | 1998 | 32,000 | 1997 | 34,700 | 1996 | 31,700 | 1995 | 16,600 | 1994 | 15,300 | 1993 | 12,600 | 1992 | 14,000 | 1991 | 15,100 | 1990 | 15,600 | 1989 | 16,100 | 1988 | 15,900 | 1987 | 15,300 | 1986 | 17,400 | 1985 | 15,400 | 1984 | 14,900 | 1983 | 15,500 | 1982 | 15,000 | 1981 | 16,700 | 1980 | 18,500 | 1979 | 17,800 | 1978 | 16,400 | 1977 | 14,800 | 1976 | 13,800 | 1975 | 14,600 | 1974 | 11,400 | 1973 | 11,500 | 1972 | 11,900 | 1971 | 11,500 | 1970 | 11,800 |
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