Year | Value | 2021 | 18,720 | 2020 | 18,720 | 2019 | 18,720 | 2018 | 18,720 | 2017 | 18,720 | 2016 | 18,720 | 2015 | 18,720 | 2014 | 18,722 | 2013 | 18,722 | 2012 | 18,722 | 2011 | 18,732 | 2010 | 18,740 | 2009 | 18,750 | 2008 | 18,760 | 2007 | 18,760 | 2006 | 18,810 | 2005 | 18,820 | 2004 | 18,840 | 2003 | 18,850 | 2002 | 18,870 | 2001 | 18,890 | 2000 | 18,890 | 1999 | 18,890 | 1998 | 18,910 | 1997 | 18,950 | 1996 | 18,970 | 1995 | 18,990 | 1994 | 19,000 | 1993 | 19,000 | 1992 | 19,010 | 1991 | 19,010 | 1990 | 19,010 | 1989 | 19,000 | 1988 | 19,000 | 1987 | 19,000 | 1986 | 19,000 | 1985 | 19,000 | 1984 | 19,000 | 1983 | 19,000 | 1982 | 19,000 | 1981 | 19,000 | 1980 | 19,000 | 1979 | 19,110 | 1978 | 19,210 | 1977 | 19,310 | 1976 | 19,400 | 1975 | 19,500 | 1974 | 19,600 | 1973 | 19,710 | 1972 | 19,810 | 1971 | 19,910 | 1970 | 20,010 | 1969 | 21,200 | 1968 | 21,200 | 1967 | 21,200 | 1966 | 21,200 | 1965 | 21,200 | 1964 | 21,200 | 1963 | 21,200 | 1962 | 21,200 | 1961 | 21,200 |
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