| Year | Value | | 2018 | 11,829 | | 2017 | 11,618 | | 2016 | 11,353 | | 2015 | 10,974 | | 2014 | 10,428 | | 2013 | 9,707 | | 2012 | 8,892 | | 2011 | 8,113 | | 2010 | 7,459 | | 2009 | 6,686 | | 2008 | 6,173 | | 2007 | 5,890 | | 2006 | 5,690 | | 2005 | 5,440 | | 2004 | 5,089 | | 2003 | 4,577 | | 2002 | 3,985 | | 2001 | 3,438 | | 2000 | 3,021 | | 1999 | 2,684 | | 1998 | 2,435 | | 1997 | 2,292 | | 1996 | 2,264 | | 1995 | 2,347 | | 1994 | 2,580 | | 1993 | 2,941 | | 1992 | 3,363 | | 1991 | 3,743 | | 1990 | 4,031 | | 1989 | 4,193 | | 1988 | 4,245 | | 1987 | 4,224 | | 1986 | 4,190 | | 1985 | 4,183 | | 1984 | 4,175 | | 1983 | 4,184 | | 1982 | 4,180 | | 1981 | 4,110 | | 1980 | 3,946 | | 1979 | 3,726 | | 1978 | 3,399 | | 1977 | 3,033 | | 1976 | 2,736 | | 1975 | 2,583 | | 1974 | 2,562 | | 1973 | 2,694 | | 1972 | 2,932 | | 1971 | 3,170 | | 1970 | 3,338 | | 1969 | 3,503 | | 1968 | 3,600 | | 1967 | 3,655 | | 1966 | 3,738 | | 1965 | 3,894 | | 1964 | 4,068 | | 1963 | 4,317 | | 1962 | 4,593 | | 1961 | 4,788 | | 1960 | 4,830 |
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