| Year | Value | | 2022 | 17,576 | | 2021 | 17,654 | | 2020 | 17,354 | | 2019 | 16,701 | | 2018 | 15,873 | | 2017 | 14,950 | | 2016 | 14,086 | | 2015 | 13,388 | | 2014 | 12,909 | | 2013 | 12,740 | | 2012 | 12,846 | | 2011 | 13,013 | | 2010 | 13,073 | | 2009 | 12,993 | | 2008 | 12,727 | | 2007 | 12,305 | | 2006 | 11,939 | | 2005 | 11,770 | | 2004 | 11,765 | | 2003 | 11,876 | | 2002 | 12,099 | | 2001 | 12,341 | | 2000 | 12,538 | | 1999 | 12,715 | | 1998 | 12,899 | | 1997 | 13,075 | | 1996 | 13,279 | | 1995 | 13,567 | | 1994 | 13,970 | | 1993 | 14,497 | | 1992 | 15,067 | | 1991 | 15,463 | | 1990 | 15,537 | | 1989 | 15,281 | | 1988 | 14,686 | | 1987 | 13,871 | | 1986 | 13,147 | | 1985 | 12,705 | | 1984 | 12,548 | | 1983 | 12,687 | | 1982 | 12,986 | | 1981 | 13,162 | | 1980 | 13,064 | | 1979 | 12,685 | | 1978 | 12,024 | | 1977 | 11,152 | | 1976 | 10,287 | | 1975 | 9,600 | | 1974 | 9,075 | | 1973 | 8,683 | | 1972 | 8,413 | | 1971 | 8,140 | | 1970 | 7,784 | | 1969 | 7,359 | | 1968 | 6,858 | | 1967 | 6,297 | | 1966 | 5,784 | | 1965 | 5,408 | | 1964 | 5,176 | | 1963 | 5,102 | | 1962 | 5,153 | | 1961 | 5,200 | | 1960 | 5,152 |
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