| Year | Value | | 2022 | 15,479 | | 2021 | 15,489 | | 2020 | 15,578 | | 2019 | 15,633 | | 2018 | 15,537 | | 2017 | 15,486 | | 2016 | 15,495 | | 2015 | 15,406 | | 2014 | 15,370 | | 2013 | 15,493 | | 2012 | 15,641 | | 2011 | 15,770 | | 2010 | 15,910 | | 2009 | 15,858 | | 2008 | 15,550 | | 2007 | 15,220 | | 2006 | 14,905 | | 2005 | 14,604 | | 2004 | 14,494 | | 2003 | 14,529 | | 2002 | 14,545 | | 2001 | 14,496 | | 2000 | 14,319 | | 1999 | 14,026 | | 1998 | 13,619 | | 1997 | 13,100 | | 1996 | 12,524 | | 1995 | 11,939 | | 1994 | 11,355 | | 1993 | 10,750 | | 1992 | 10,110 | | 1991 | 9,464 | | 1990 | 8,900 | | 1989 | 8,372 | | 1988 | 7,899 | | 1987 | 7,547 | | 1986 | 7,277 | | 1985 | 7,073 | | 1984 | 6,958 | | 1983 | 6,951 | | 1982 | 7,005 | | 1981 | 7,081 | | 1980 | 7,060 | | 1979 | 6,915 | | 1978 | 6,710 | | 1977 | 6,465 | | 1976 | 6,192 | | 1975 | 5,926 | | 1974 | 5,685 | | 1973 | 5,470 | | 1972 | 5,274 | | 1971 | 5,088 | | 1970 | 4,899 | | 1969 | 4,698 | | 1968 | 4,492 | | 1967 | 4,289 | | 1966 | 4,091 | | 1965 | 3,911 | | 1964 | 3,758 | | 1963 | 3,619 | | 1962 | 3,487 | | 1961 | 3,371 | | 1960 | 3,276 |
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