| Year | Value | | 2022 | 15,095 | | 2021 | 14,509 | | 2020 | 14,795 | | 2019 | 15,805 | | 2018 | 17,148 | | 2017 | 18,312 | | 2016 | 18,953 | | 2015 | 19,039 | | 2014 | 18,694 | | 2013 | 18,033 | | 2012 | 17,227 | | 2011 | 16,519 | | 2010 | 16,072 | | 2009 | 15,899 | | 2008 | 15,937 | | 2007 | 16,029 | | 2006 | 15,949 | | 2005 | 15,577 | | 2004 | 14,840 | | 2003 | 13,744 | | 2002 | 12,462 | | 2001 | 11,158 | | 2000 | 9,958 | | 1999 | 8,986 | | 1998 | 8,272 | | 1997 | 7,765 | | 1996 | 7,452 | | 1995 | 7,306 | | 1994 | 7,297 | | 1993 | 7,452 | | 1992 | 7,771 | | 1991 | 8,179 | | 1990 | 8,570 | | 1989 | 8,855 | | 1988 | 9,008 | | 1987 | 9,013 | | 1986 | 8,915 | | 1985 | 8,864 | | 1984 | 8,894 | | 1983 | 8,980 | | 1982 | 9,080 | | 1981 | 9,098 | | 1980 | 8,971 | | 1979 | 8,748 | | 1978 | 8,445 | | 1977 | 8,062 | | 1976 | 7,678 | | 1975 | 7,357 | | 1974 | 7,092 | | 1973 | 6,878 | | 1972 | 6,743 | | 1971 | 6,694 | | 1970 | 6,735 | | 1969 | 6,891 | | 1968 | 7,194 | | 1967 | 7,587 | | 1966 | 7,933 | | 1965 | 8,128 | | 1964 | 8,151 | | 1963 | 7,977 | | 1962 | 7,632 | | 1961 | 7,239 | | 1960 | 6,896 |
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