| Year | Value | | 2018 | 13,366 | | 2017 | 13,003 | | 2016 | 12,660 | | 2015 | 12,332 | | 2014 | 11,984 | | 2013 | 11,639 | | 2012 | 11,303 | | 2011 | 10,963 | | 2010 | 10,621 | | 2009 | 10,245 | | 2008 | 9,868 | | 2007 | 9,484 | | 2006 | 9,087 | | 2005 | 8,674 | | 2004 | 8,219 | | 2003 | 7,737 | | 2002 | 7,266 | | 2001 | 6,863 | | 2000 | 6,570 | | 1999 | 6,358 | | 1998 | 6,261 | | 1997 | 6,242 | | 1996 | 6,236 | | 1995 | 6,200 | | 1994 | 6,126 | | 1993 | 6,023 | | 1992 | 5,904 | | 1991 | 5,788 | | 1990 | 5,690 | | 1989 | 5,585 | | 1988 | 5,484 | | 1987 | 5,389 | | 1986 | 5,302 | | 1985 | 5,226 | | 1984 | 5,136 | | 1983 | 5,055 | | 1982 | 4,977 | | 1981 | 4,898 | | 1980 | 4,814 | | 1979 | 4,699 | | 1978 | 4,577 | | 1977 | 4,460 | | 1976 | 4,355 | | 1975 | 4,275 | | 1974 | 4,207 | | 1973 | 4,158 | | 1972 | 4,127 | | 1971 | 4,103 | | 1970 | 4,078 | | 1969 | 4,029 | | 1968 | 3,976 | | 1967 | 3,921 | | 1966 | 3,868 | | 1965 | 3,824 | | 1964 | 3,764 | | 1963 | 3,708 | | 1962 | 3,653 | | 1961 | 3,594 | | 1960 | 3,530 |
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