| Year | Value | | 2022 | 19,490 | | 2021 | 19,287 | | 2020 | 19,039 | | 2019 | 18,536 | | 2018 | 17,854 | | 2017 | 17,213 | | 2016 | 16,644 | | 2015 | 16,146 | | 2014 | 15,720 | | 2013 | 15,401 | | 2012 | 15,145 | | 2011 | 14,923 | | 2010 | 14,796 | | 2009 | 14,706 | | 2008 | 14,632 | | 2007 | 14,612 | | 2006 | 14,566 | | 2005 | 14,419 | | 2004 | 14,204 | | 2003 | 13,951 | | 2002 | 13,683 | | 2001 | 13,412 | | 2000 | 13,137 | | 1999 | 12,859 | | 1998 | 12,566 | | 1997 | 12,327 | | 1996 | 12,158 | | 1995 | 11,961 | | 1994 | 11,735 | | 1993 | 11,502 | | 1992 | 11,250 | | 1991 | 10,989 | | 1990 | 10,712 | | 1989 | 10,418 | | 1988 | 10,117 | | 1987 | 9,800 | | 1986 | 9,451 | | 1985 | 9,063 | | 1984 | 8,647 | | 1983 | 8,226 | | 1982 | 7,821 | | 1981 | 7,436 | | 1980 | 7,073 | | 1979 | 6,729 | | 1978 | 6,404 | | 1977 | 6,102 | | 1976 | 5,806 | | 1975 | 5,530 | | 1974 | 5,290 | | 1973 | 5,075 | | 1972 | 4,880 | | 1971 | 4,690 | | 1970 | 4,511 | | 1969 | 4,338 | | 1968 | 4,175 | | 1967 | 4,022 | | 1966 | 3,871 | | 1965 | 3,721 | | 1964 | 3,565 | | 1963 | 3,393 | | 1962 | 3,209 | | 1961 | 3,004 | | 1960 | 2,764 |
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