| Year | Value | | 2022 | 25,434 | | 2021 | 25,648 | | 2020 | 25,828 | | 2019 | 25,617 | | 2018 | 25,071 | | 2017 | 24,532 | | 2016 | 24,007 | | 2015 | 23,508 | | 2014 | 23,067 | | 2013 | 22,660 | | 2012 | 22,287 | | 2011 | 21,909 | | 2010 | 21,509 | | 2009 | 21,098 | | 2008 | 20,659 | | 2007 | 20,198 | | 2006 | 19,747 | | 2005 | 19,390 | | 2004 | 19,056 | | 2003 | 18,609 | | 2002 | 18,065 | | 2001 | 17,829 | | 2000 | 17,737 | | 1999 | 17,347 | | 1998 | 16,810 | | 1997 | 16,513 | | 1996 | 16,223 | | 1995 | 15,625 | | 1994 | 15,054 | | 1993 | 14,461 | | 1992 | 13,853 | | 1991 | 13,255 | | 1990 | 12,573 | | 1989 | 11,992 | | 1988 | 11,537 | | 1987 | 11,082 | | 1986 | 10,641 | | 1985 | 10,223 | | 1984 | 9,835 | | 1983 | 9,481 | | 1982 | 9,157 | | 1981 | 8,879 | | 1980 | 8,653 | | 1979 | 8,479 | | 1978 | 8,354 | | 1977 | 8,278 | | 1976 | 8,238 | | 1975 | 8,219 | | 1974 | 8,231 | | 1973 | 8,269 | | 1972 | 8,331 | | 1971 | 8,425 | | 1970 | 8,553 | | 1969 | 8,697 | | 1968 | 8,853 | | 1967 | 9,040 | | 1966 | 9,246 | | 1965 | 9,438 | | 1964 | 9,611 | | 1963 | 9,753 | | 1962 | 9,846 | | 1961 | 9,881 | | 1960 | 9,850 |
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