| Year | Value | | 2022 | 6,391 | | 2021 | 6,432 | | 2020 | 6,452 | | 2019 | 6,488 | | 2018 | 6,530 | | 2017 | 6,544 | | 2016 | 6,486 | | 2015 | 6,336 | | 2014 | 6,146 | | 2013 | 5,952 | | 2012 | 5,783 | | 2011 | 5,637 | | 2010 | 5,493 | | 2009 | 5,354 | | 2008 | 5,219 | | 2007 | 5,076 | | 2006 | 4,976 | | 2005 | 4,940 | | 2004 | 4,934 | | 2003 | 4,978 | | 2002 | 5,100 | | 2001 | 5,220 | | 2000 | 5,209 | | 1999 | 5,068 | | 1998 | 4,836 | | 1997 | 4,518 | | 1996 | 4,200 | | 1995 | 4,001 | | 1994 | 3,950 | | 1993 | 3,988 | | 1992 | 4,052 | | 1991 | 4,115 | | 1990 | 4,121 | | 1989 | 4,067 | | 1988 | 4,002 | | 1987 | 3,918 | | 1986 | 3,809 | | 1985 | 3,703 | | 1984 | 3,625 | | 1983 | 3,554 | | 1982 | 3,502 | | 1981 | 3,490 | | 1980 | 3,497 | | 1979 | 3,531 | | 1978 | 3,602 | | 1977 | 3,656 | | 1976 | 3,647 | | 1975 | 3,573 | | 1974 | 3,461 | | 1973 | 3,356 | | 1972 | 3,281 | | 1971 | 3,237 | | 1970 | 3,203 | | 1969 | 3,224 | | 1968 | 3,333 | | 1967 | 3,488 | | 1966 | 3,645 | | 1965 | 3,768 | | 1964 | 3,837 | | 1963 | 3,866 | | 1962 | 3,864 | | 1961 | 3,825 | | 1960 | 3,735 |
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