| Year | Value | | 2022 | 17,536 | | 2021 | 17,908 | | 2020 | 18,208 | | 2019 | 18,400 | | 2018 | 18,483 | | 2017 | 18,467 | | 2016 | 18,397 | | 2015 | 18,307 | | 2014 | 18,197 | | 2013 | 18,054 | | 2012 | 17,864 | | 2011 | 17,633 | | 2010 | 17,232 | | 2009 | 16,685 | | 2008 | 16,162 | | 2007 | 15,690 | | 2006 | 15,276 | | 2005 | 14,916 | | 2004 | 14,600 | | 2003 | 14,317 | | 2002 | 14,055 | | 2001 | 13,800 | | 2000 | 13,541 | | 1999 | 13,280 | | 1998 | 13,047 | | 1997 | 12,872 | | 1996 | 12,756 | | 1995 | 12,689 | | 1994 | 12,644 | | 1993 | 12,570 | | 1992 | 12,421 | | 1991 | 12,091 | | 1990 | 11,539 | | 1989 | 10,906 | | 1988 | 10,274 | | 1987 | 9,651 | | 1986 | 9,039 | | 1985 | 8,430 | | 1984 | 7,835 | | 1983 | 7,276 | | 1982 | 6,751 | | 1981 | 6,224 | | 1980 | 5,685 | | 1979 | 5,167 | | 1978 | 4,722 | | 1977 | 4,387 | | 1976 | 4,170 | | 1975 | 4,047 | | 1974 | 3,969 | | 1973 | 3,903 | | 1972 | 3,834 | | 1971 | 3,739 | | 1970 | 3,615 | | 1969 | 3,493 | | 1968 | 3,393 | | 1967 | 3,302 | | 1966 | 3,205 | | 1965 | 3,090 | | 1964 | 2,961 | | 1963 | 2,830 | | 1962 | 2,704 | | 1961 | 2,593 | | 1960 | 2,479 |
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