| Year | Value | | 2018 | 3,593 | | 2017 | 3,578 | | 2016 | 3,584 | | 2015 | 3,575 | | 2014 | 3,520 | | 2013 | 3,450 | | 2012 | 3,372 | | 2011 | 3,300 | | 2010 | 3,242 | | 2009 | 3,166 | | 2008 | 3,098 | | 2007 | 3,037 | | 2006 | 2,986 | | 2005 | 2,937 | | 2004 | 2,867 | | 2003 | 2,807 | | 2002 | 2,752 | | 2001 | 2,704 | | 2000 | 2,658 | | 1999 | 2,594 | | 1998 | 2,534 | | 1997 | 2,484 | | 1996 | 2,438 | | 1995 | 2,395 | | 1994 | 2,338 | | 1993 | 2,287 | | 1992 | 2,245 | | 1991 | 2,203 | | 1990 | 2,165 | | 1989 | 2,112 | | 1988 | 2,062 | | 1987 | 2,012 | | 1986 | 1,966 | | 1985 | 1,924 | | 1984 | 1,867 | | 1983 | 1,817 | | 1982 | 1,767 | | 1981 | 1,714 | | 1980 | 1,656 | | 1979 | 1,578 | | 1978 | 1,501 | | 1977 | 1,423 | | 1976 | 1,354 | | 1975 | 1,295 | | 1974 | 1,242 | | 1973 | 1,202 | | 1972 | 1,170 | | 1971 | 1,144 | | 1970 | 1,120 | | 1969 | 1,095 | | 1968 | 1,071 | | 1967 | 1,053 | | 1966 | 1,037 | | 1965 | 1,022 | | 1964 | 1,010 | | 1963 | 999 | | 1962 | 989 | | 1961 | 981 | | 1960 | 975 |
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