| Year | Value | | 2022 | 20,474 | | 2021 | 20,022 | | 2020 | 19,566 | | 2019 | 18,995 | | 2018 | 18,380 | | 2017 | 17,865 | | 2016 | 17,415 | | 2015 | 16,995 | | 2014 | 16,593 | | 2013 | 16,185 | | 2012 | 15,773 | | 2011 | 15,378 | | 2010 | 15,009 | | 2009 | 14,651 | | 2008 | 14,317 | | 2007 | 14,033 | | 2006 | 13,810 | | 2005 | 13,613 | | 2004 | 13,378 | | 2003 | 13,067 | | 2002 | 12,688 | | 2001 | 12,116 | | 2000 | 11,557 | | 1999 | 11,443 | | 1998 | 11,570 | | 1997 | 11,622 | | 1996 | 11,619 | | 1995 | 11,715 | | 1994 | 11,856 | | 1993 | 11,958 | | 1992 | 12,118 | | 1991 | 12,479 | | 1990 | 12,453 | | 1989 | 12,083 | | 1988 | 11,888 | | 1987 | 11,665 | | 1986 | 11,438 | | 1985 | 11,231 | | 1984 | 11,044 | | 1983 | 10,853 | | 1982 | 10,661 | | 1981 | 10,469 | | 1980 | 10,273 | | 1979 | 10,075 | | 1978 | 9,879 | | 1977 | 9,690 | | 1976 | 9,498 | | 1975 | 9,306 | | 1974 | 9,113 | | 1973 | 8,913 | | 1972 | 8,702 | | 1971 | 8,484 | | 1970 | 8,264 | | 1969 | 8,043 | | 1968 | 7,823 | | 1967 | 7,601 | | 1966 | 7,381 | | 1965 | 7,164 | | 1964 | 6,947 | | 1963 | 6,727 | | 1962 | 6,502 | | 1961 | 6,271 | | 1960 | 6,032 |
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