Year | Value | 2021 | 17,950 | 2020 | 17,900 | 2019 | 17,900 | 2018 | 19,950 | 2017 | 20,100 | 2016 | 20,680 | 2015 | 20,680 | 2014 | 20,680 | 2013 | 20,680 | 2012 | 20,240 | 2011 | 20,090 | 2010 | 19,840 | 2009 | 18,163.3 | 2008 | 17,700 | 2007 | 17,700 | 2006 | 17,700 | 2005 | 17,700 | 2004 | 16,700 | 2003 | 16,700 | 2002 | 16,700 | 2001 | 16,700 | 2000 | 16,900 | 1999 | 16,900 | 1998 | 16,900 | 1997 | 16,900 | 1996 | 15,900 | 1995 | 15,900 | 1994 | 15,950 | 1993 | 15,750 | 1992 | 15,750 | 1991 | 15,960 | 1990 | 15,970 | 1989 | 15,980 | 1988 | 15,990 | 1987 | 16,000 | 1986 | 16,000 | 1985 | 16,000 | 1984 | 16,000 | 1983 | 16,000 | 1982 | 16,000 | 1981 | 16,000 | 1980 | 16,000 | 1979 | 15,950 | 1978 | 15,950 | 1977 | 15,850 | 1976 | 15,850 | 1975 | 15,830 | 1974 | 15,830 | 1973 | 15,830 | 1972 | 15,840 | 1971 | 17,100 | 1970 | 17,050 | 1969 | 17,000 | 1968 | 16,950 | 1967 | 16,900 | 1966 | 16,850 | 1965 | 16,800 | 1964 | 16,750 | 1963 | 16,700 | 1962 | 16,650 | 1961 | 16,600 |
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