| Year | Value | | 2022 | 20,639 | | 2021 | 20,401 | | 2020 | 20,141 | | 2019 | 19,618 | | 2018 | 18,940 | | 2017 | 18,341 | | 2016 | 17,795 | | 2015 | 17,284 | | 2014 | 16,807 | | 2013 | 16,368 | | 2012 | 15,957 | | 2011 | 15,574 | | 2010 | 15,229 | | 2009 | 14,921 | | 2008 | 14,638 | | 2007 | 14,367 | | 2006 | 14,158 | | 2005 | 13,924 | | 2004 | 13,649 | | 2003 | 13,409 | | 2002 | 13,170 | | 2001 | 12,927 | | 2000 | 12,685 | | 1999 | 12,438 | | 1998 | 12,186 | | 1997 | 11,926 | | 1996 | 11,685 | | 1995 | 11,573 | | 1994 | 11,721 | | 1993 | 11,396 | | 1992 | 10,808 | | 1991 | 10,592 | | 1990 | 10,366 | | 1989 | 10,132 | | 1988 | 9,892 | | 1987 | 9,653 | | 1986 | 9,426 | | 1985 | 9,205 | | 1984 | 8,993 | | 1983 | 8,782 | | 1982 | 8,563 | | 1981 | 8,353 | | 1980 | 8,166 | | 1979 | 8,006 | | 1978 | 7,868 | | 1977 | 7,748 | | 1976 | 7,636 | | 1975 | 7,528 | | 1974 | 7,430 | | 1973 | 7,329 | | 1972 | 7,232 | | 1971 | 7,161 | | 1970 | 7,127 | | 1969 | 7,129 | | 1968 | 7,176 | | 1967 | 7,271 | | 1966 | 7,394 | | 1965 | 7,533 | | 1964 | 7,690 | | 1963 | 7,873 | | 1962 | 8,077 | | 1961 | 8,309 | | 1960 | 8,576 |
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