| Year | Value | | 2022 | 18,392 | | 2021 | 18,044 | | 2020 | 17,536 | | 2019 | 16,900 | | 2018 | 16,200 | | 2017 | 15,525 | | 2016 | 14,870 | | 2015 | 14,243 | | 2014 | 13,666 | | 2013 | 13,147 | | 2012 | 12,709 | | 2011 | 12,374 | | 2010 | 12,129 | | 2009 | 11,975 | | 2008 | 11,918 | | 2007 | 11,993 | | 2006 | 12,194 | | 2005 | 12,463 | | 2004 | 12,750 | | 2003 | 12,886 | | 2002 | 12,857 | | 2001 | 12,734 | | 2000 | 12,469 | | 1999 | 12,093 | | 1998 | 11,787 | | 1997 | 11,626 | | 1996 | 11,458 | | 1995 | 11,214 | | 1994 | 11,226 | | 1993 | 11,219 | | 1992 | 10,808 | | 1991 | 10,265 | | 1990 | 9,687 | | 1989 | 9,196 | | 1988 | 8,640 | | 1987 | 8,016 | | 1986 | 7,503 | | 1985 | 7,008 | | 1984 | 6,591 | | 1983 | 6,273 | | 1982 | 5,996 | | 1981 | 5,836 | | 1980 | 5,729 | | 1979 | 5,593 | | 1978 | 5,486 | | 1977 | 5,415 | | 1976 | 5,362 | | 1975 | 5,316 | | 1974 | 5,291 | | 1973 | 5,282 | | 1972 | 5,279 | | 1971 | 5,270 | | 1970 | 5,245 | | 1969 | 5,202 | | 1968 | 5,139 | | 1967 | 5,061 | | 1966 | 4,982 | | 1965 | 4,915 | | 1964 | 4,860 | | 1963 | 4,821 | | 1962 | 4,790 | | 1961 | 4,752 | | 1960 | 4,699 |
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