| Year | Value | | 2021 | 5,130 | | 2020 | 5,130 | | 2019 | 5,130 | | 2018 | 5,130 | | 2017 | 5,130 | | 2016 | 5,190 | | 2015 | 5,256 | | 2014 | 5,256 | | 2013 | 5,196 | | 2012 | 5,196 | | 2011 | 5,196 | | 2010 | 5,200 | | 2009 | 5,200 | | 2008 | 5,213 | | 2007 | 5,630 | | 2006 | 5,770 | | 2005 | 5,930 | | 2004 | 5,840 | | 2003 | 5,830 | | 2002 | 5,800 | | 2001 | 5,790 | | 2000 | 5,780 | | 1999 | 5,720 | | 1998 | 5,720 | | 1997 | 5,720 | | 1996 | 5,700 | | 1995 | 5,650 | | 1994 | 5,090 | | 1993 | 5,050 | | 1992 | 5,040 | | 1991 | 5,040 | | 1990 | 4,540 | | 1989 | 4,520 | | 1988 | 4,600 | | 1987 | 4,650 | | 1986 | 4,440 | | 1985 | 4,440 | | 1984 | 4,440 | | 1983 | 4,300 | | 1982 | 4,180 | | 1981 | 4,130 | | 1980 | 4,130 | | 1979 | 4,050 | | 1978 | 4,000 | | 1977 | 4,000 | | 1976 | 3,980 | | 1975 | 3,920 | | 1974 | 3,920 | | 1973 | 3,850 | | 1972 | 3,850 | | 1971 | 3,820 | | 1970 | 3,820 | | 1969 | 3,700 | | 1968 | 3,700 | | 1967 | 3,680 | | 1966 | 3,680 | | 1965 | 3,660 | | 1964 | 3,650 | | 1963 | 3,630 | | 1962 | 3,630 | | 1961 | 3,610 |
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