| Year | Value | | 2022 | 19,664 | | 2021 | 19,760 | | 2020 | 19,885 | | 2019 | 19,950 | | 2018 | 19,899 | | 2017 | 19,743 | | 2016 | 19,468 | | 2015 | 19,132 | | 2014 | 18,778 | | 2013 | 18,427 | | 2012 | 18,092 | | 2011 | 17,735 | | 2010 | 17,307 | | 2009 | 16,837 | | 2008 | 16,374 | | 2007 | 15,933 | | 2006 | 15,518 | | 2005 | 15,135 | | 2004 | 14,785 | | 2003 | 14,432 | | 2002 | 14,028 | | 2001 | 13,556 | | 2000 | 13,120 | | 1999 | 12,774 | | 1998 | 12,498 | | 1997 | 12,322 | | 1996 | 12,145 | | 1995 | 11,855 | | 1994 | 11,471 | | 1993 | 11,008 | | 1992 | 10,470 | | 1991 | 10,097 | | 1990 | 9,875 | | 1989 | 9,615 | | 1988 | 9,411 | | 1987 | 9,298 | | 1986 | 9,275 | | 1985 | 9,349 | | 1984 | 9,497 | | 1983 | 9,622 | | 1982 | 9,667 | | 1981 | 9,623 | | 1980 | 9,441 | | 1979 | 9,161 | | 1978 | 8,827 | | 1977 | 8,435 | | 1976 | 8,026 | | 1975 | 7,627 | | 1974 | 7,292 | | 1973 | 7,040 | | 1972 | 6,820 | | 1971 | 6,594 | | 1970 | 6,311 | | 1969 | 5,981 | | 1968 | 5,642 | | 1967 | 5,315 | | 1966 | 5,014 | | 1965 | 4,755 | | 1964 | 4,522 | | 1963 | 4,315 | | 1962 | 4,144 | | 1961 | 4,009 | | 1960 | 3,895 |
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