| Year | Value | | 2021 | 1,689 | | 2020 | 1,689 | | 2019 | 1,689 | | 2018 | 1,689 | | 2017 | 1,738 | | 2016 | 1,784 | | 2015 | 1,830 | | 2014 | 1,876 | | 2013 | 1,922 | | 2012 | 1,968 | | 2011 | 1,955 | | 2010 | 1,939 | | 2009 | 1,923 | | 2008 | 1,907 | | 2007 | 1,890 | | 2006 | 1,958 | | 2005 | 2,024 | | 2004 | 2,090 | | 2003 | 2,156 | | 2002 | 2,220 | | 2001 | 2,347 | | 2000 | 2,472 | | 1999 | 2,599 | | 1998 | 2,725 | | 1997 | 2,910 | | 1996 | 3,090 | | 1995 | 3,090 | | 1994 | 3,090 | | 1993 | 3,110 | | 1992 | 4,100 | | 1991 | 4,200 | | 1990 | 4,350 | | 1989 | 4,500 | | 1988 | 4,620 | | 1987 | 4,620 | | 1986 | 4,630 | | 1985 | 4,610 | | 1984 | 4,640 | | 1983 | 4,660 | | 1982 | 4,670 | | 1981 | 4,670 | | 1980 | 4,750 | | 1979 | 4,860 | | 1978 | 4,950 | | 1977 | 4,910 | | 1976 | 4,930 | | 1975 | 4,930 | | 1974 | 4,940 | | 1973 | 4,920 | | 1972 | 5,150 | | 1971 | 5,300 | | 1970 | 5,520 | | 1969 | 5,620 | | 1968 | 5,660 | | 1967 | 5,680 | | 1966 | 5,810 | | 1965 | 6,090 | | 1964 | 5,850 | | 1963 | 6,050 | | 1962 | 6,010 | | 1961 | 6,160 |
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