| Year | Value | | 2022 | 22,711 | | 2021 | 22,522 | | 2020 | 22,223 | | 2019 | 21,822 | | 2018 | 21,434 | | 2017 | 21,053 | | 2016 | 20,680 | | 2015 | 20,326 | | 2014 | 20,113 | | 2013 | 20,027 | | 2012 | 19,950 | | 2011 | 19,881 | | 2010 | 19,812 | | 2009 | 19,726 | | 2008 | 19,624 | | 2007 | 19,509 | | 2006 | 19,396 | | 2005 | 19,211 | | 2004 | 18,834 | | 2003 | 18,347 | | 2002 | 17,799 | | 2001 | 17,192 | | 2000 | 16,591 | | 1999 | 16,210 | | 1998 | 15,996 | | 1997 | 15,731 | | 1996 | 15,370 | | 1995 | 14,925 | | 1994 | 14,709 | | 1993 | 14,699 | | 1992 | 14,663 | | 1991 | 14,583 | | 1990 | 14,526 | | 1989 | 14,452 | | 1988 | 14,330 | | 1987 | 14,221 | | 1986 | 14,117 | | 1985 | 14,022 | | 1984 | 13,924 | | 1983 | 13,817 | | 1982 | 13,698 | | 1981 | 13,564 | | 1980 | 13,427 | | 1979 | 13,292 | | 1978 | 13,158 | | 1977 | 12,986 | | 1976 | 12,651 | | 1975 | 12,320 | | 1974 | 11,993 | | 1973 | 11,670 | | 1972 | 11,354 | | 1971 | 11,043 | | 1970 | 10,738 | | 1969 | 10,462 | | 1968 | 10,206 | | 1967 | 9,950 | | 1966 | 9,695 | | 1965 | 9,287 | | 1964 | 8,842 | | 1963 | 8,423 | | 1962 | 8,028 | | 1961 | 7,655 | | 1960 | 7,303 |
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