| Year | Value | | 2018 | 16,144 | | 2017 | 15,678 | | 2016 | 15,247 | | 2015 | 14,851 | | 2014 | 14,438 | | 2013 | 14,047 | | 2012 | 13,673 | | 2011 | 13,314 | | 2010 | 12,971 | | 2009 | 12,606 | | 2008 | 12,248 | | 2007 | 11,894 | | 2006 | 11,541 | | 2005 | 11,183 | | 2004 | 10,794 | | 2003 | 10,403 | | 2002 | 10,007 | | 2001 | 9,601 | | 2000 | 9,187 | | 1999 | 8,729 | | 1998 | 8,257 | | 1997 | 7,795 | | 1996 | 7,392 | | 1995 | 7,076 | | 1994 | 6,829 | | 1993 | 6,674 | | 1992 | 6,587 | | 1991 | 6,527 | | 1990 | 6,458 | | 1989 | 6,373 | | 1988 | 6,282 | | 1987 | 6,185 | | 1986 | 6,089 | | 1985 | 6,000 | | 1984 | 5,886 | | 1983 | 5,763 | | 1982 | 5,634 | | 1981 | 5,505 | | 1980 | 5,380 | | 1979 | 5,231 | | 1978 | 5,086 | | 1977 | 4,949 | | 1976 | 4,826 | | 1975 | 4,728 | | 1974 | 4,639 | | 1973 | 4,570 | | 1972 | 4,518 | | 1971 | 4,480 | | 1970 | 4,448 | | 1969 | 4,403 | | 1968 | 4,361 | | 1967 | 4,325 | | 1966 | 4,294 | | 1965 | 4,269 | | 1964 | 4,231 | | 1963 | 4,193 | | 1962 | 4,158 | | 1961 | 4,125 | | 1960 | 4,094 |
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