| Year | Value | | 2022 | 24,125 | | 2021 | 23,338 | | 2020 | 22,543 | | 2019 | 21,750 | | 2018 | 21,009 | | 2017 | 20,328 | | 2016 | 19,651 | | 2015 | 18,992 | | 2014 | 18,358 | | 2013 | 17,759 | | 2012 | 17,200 | | 2011 | 16,658 | | 2010 | 16,124 | | 2009 | 15,615 | | 2008 | 15,147 | | 2007 | 14,750 | | 2006 | 14,456 | | 2005 | 14,265 | | 2004 | 14,183 | | 2003 | 14,202 | | 2002 | 14,313 | | 2001 | 14,485 | | 2000 | 14,689 | | 1999 | 14,880 | | 1998 | 14,871 | | 1997 | 14,677 | | 1996 | 14,488 | | 1995 | 14,225 | | 1994 | 14,277 | | 1993 | 14,402 | | 1992 | 14,001 | | 1991 | 13,378 | | 1990 | 12,730 | | 1989 | 12,238 | | 1988 | 11,682 | | 1987 | 11,041 | | 1986 | 10,532 | | 1985 | 10,016 | | 1984 | 9,517 | | 1983 | 9,041 | | 1982 | 8,572 | | 1981 | 8,160 | | 1980 | 7,796 | | 1979 | 7,444 | | 1978 | 7,126 | | 1977 | 6,848 | | 1976 | 6,629 | | 1975 | 6,465 | | 1974 | 6,333 | | 1973 | 6,225 | | 1972 | 6,142 | | 1971 | 6,082 | | 1970 | 6,043 | | 1969 | 6,019 | | 1968 | 6,010 | | 1967 | 5,999 | | 1966 | 5,977 | | 1965 | 5,944 | | 1964 | 5,898 | | 1963 | 5,845 | | 1962 | 5,784 | | 1961 | 5,721 | | 1960 | 5,664 |
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