| Year | Value | | 2022 | 25,509 | | 2021 | 24,242 | | 2020 | 23,201 | | 2019 | 21,977 | | 2018 | 20,478 | | 2017 | 19,096 | | 2016 | 18,096 | | 2015 | 17,408 | | 2014 | 16,704 | | 2013 | 16,033 | | 2012 | 15,410 | | 2011 | 14,877 | | 2010 | 14,444 | | 2009 | 13,950 | | 2008 | 13,459 | | 2007 | 13,123 | | 2006 | 12,880 | | 2005 | 12,639 | | 2004 | 12,548 | | 2003 | 12,651 | | 2002 | 12,913 | | 2001 | 13,254 | | 2000 | 13,761 | | 1999 | 14,271 | | 1998 | 14,588 | | 1997 | 14,825 | | 1996 | 14,982 | | 1995 | 14,991 | | 1994 | 14,906 | | 1993 | 14,857 | | 1992 | 14,681 | | 1991 | 14,393 | | 1990 | 13,949 | | 1989 | 13,952 | | 1988 | 14,112 | | 1987 | 14,368 | | 1986 | 14,643 | | 1985 | 14,590 | | 1984 | 14,172 | | 1983 | 13,719 | | 1982 | 12,811 | | 1981 | 11,563 | | 1980 | 10,482 | | 1979 | 9,507 | | 1978 | 8,707 | | 1977 | 8,174 | | 1976 | 8,011 | | 1975 | 8,032 | | 1974 | 8,113 | | 1973 | 8,246 | | 1972 | 8,325 | | 1971 | 8,317 | | 1970 | 8,190 | | 1969 | 8,042 | | 1968 | 7,935 | | 1967 | 7,866 | | 1966 | 7,885 | | 1965 | 8,004 | | 1964 | 8,159 | | 1963 | 8,297 | | 1962 | 8,427 | | 1961 | 8,531 | | 1960 | 8,594 |
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