| Year | Value | | 2022 | 21,678 | | 2021 | 21,805 | | 2020 | 22,442 | | 2019 | 23,018 | | 2018 | 22,712 | | 2017 | 22,488 | | 2016 | 22,332 | | 2015 | 22,169 | | 2014 | 21,933 | | 2013 | 21,582 | | 2012 | 21,109 | | 2011 | 20,441 | | 2010 | 19,518 | | 2009 | 18,272 | | 2008 | 16,747 | | 2007 | 15,179 | | 2006 | 13,685 | | 2005 | 12,347 | | 2004 | 11,240 | | 2003 | 10,331 | | 2002 | 9,577 | | 2001 | 8,947 | | 2000 | 8,521 | | 1999 | 8,246 | | 1998 | 8,140 | | 1997 | 8,336 | | 1996 | 8,761 | | 1995 | 9,314 | | 1994 | 10,010 | | 1993 | 10,883 | | 1992 | 11,709 | | 1991 | 12,198 | | 1990 | 12,354 | | 1989 | 12,499 | | 1988 | 12,356 | | 1987 | 11,751 | | 1986 | 10,963 | | 1985 | 10,050 | | 1984 | 9,542 | | 1983 | 9,440 | | 1982 | 9,289 | | 1981 | 9,102 | | 1980 | 8,866 | | 1979 | 8,581 | | 1978 | 8,270 | | 1977 | 7,956 | | 1976 | 7,664 | | 1975 | 7,410 | | 1974 | 7,216 | | 1973 | 7,107 | | 1972 | 7,057 | | 1971 | 7,006 | | 1970 | 6,911 | | 1969 | 6,742 | | 1968 | 6,476 | | 1967 | 6,133 | | 1966 | 5,783 | | 1965 | 5,464 | | 1964 | 5,174 | | 1963 | 4,927 | | 1962 | 4,722 | | 1961 | 4,526 | | 1960 | 4,330 |
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