| Year | Value | | 2022 | 16,592 | | 2021 | 16,545 | | 2020 | 16,557 | | 2019 | 16,575 | | 2018 | 16,669 | | 2017 | 16,821 | | 2016 | 16,950 | | 2015 | 17,099 | | 2014 | 17,344 | | 2013 | 17,681 | | 2012 | 18,074 | | 2011 | 18,458 | | 2010 | 18,710 | | 2009 | 18,782 | | 2008 | 18,713 | | 2007 | 18,509 | | 2006 | 18,181 | | 2005 | 17,724 | | 2004 | 17,149 | | 2003 | 16,484 | | 2002 | 15,767 | | 2001 | 15,054 | | 2000 | 14,407 | | 1999 | 13,837 | | 1998 | 13,318 | | 1997 | 12,869 | | 1996 | 12,531 | | 1995 | 12,325 | | 1994 | 12,254 | | 1993 | 12,315 | | 1992 | 12,471 | | 1991 | 12,608 | | 1990 | 12,570 | | 1989 | 12,332 | | 1988 | 11,994 | | 1987 | 11,637 | | 1986 | 11,325 | | 1985 | 11,086 | | 1984 | 10,903 | | 1983 | 10,730 | | 1982 | 10,526 | | 1981 | 10,268 | | 1980 | 9,928 | | 1979 | 9,509 | | 1978 | 9,041 | | 1977 | 8,548 | | 1976 | 8,047 | | 1975 | 7,545 | | 1974 | 7,052 | | 1973 | 6,582 | | 1972 | 6,131 | | 1971 | 5,676 | | 1970 | 5,206 | | 1969 | 4,750 | | 1968 | 4,357 | | 1967 | 4,050 | | 1966 | 3,836 | | 1965 | 3,696 | | 1964 | 3,608 | | 1963 | 3,538 | | 1962 | 3,464 | | 1961 | 3,385 | | 1960 | 3,291 |
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