| Year | Value | | 2022 | 24,200 | | 2021 | 23,464 | | 2020 | 22,662 | | 2019 | 22,230 | | 2018 | 22,229 | | 2017 | 22,424 | | 2016 | 22,939 | | 2015 | 23,645 | | 2014 | 23,974 | | 2013 | 23,778 | | 2012 | 23,359 | | 2011 | 22,709 | | 2010 | 21,963 | | 2009 | 21,215 | | 2008 | 20,452 | | 2007 | 19,736 | | 2006 | 19,194 | | 2005 | 18,662 | | 2004 | 18,063 | | 2003 | 17,294 | | 2002 | 16,532 | | 2001 | 15,855 | | 2000 | 15,270 | | 1999 | 14,974 | | 1998 | 14,736 | | 1997 | 14,367 | | 1996 | 13,965 | | 1995 | 13,251 | | 1994 | 12,516 | | 1993 | 12,011 | | 1992 | 11,517 | | 1991 | 12,040 | | 1990 | 12,524 | | 1989 | 12,090 | | 1988 | 11,664 | | 1987 | 11,241 | | 1986 | 10,836 | | 1985 | 10,456 | | 1984 | 10,100 | | 1983 | 9,758 | | 1982 | 9,438 | | 1981 | 9,130 | | 1980 | 8,832 | | 1979 | 8,550 | | 1978 | 8,287 | | 1977 | 8,038 | | 1976 | 7,801 | | 1975 | 7,575 | | 1974 | 7,353 | | 1973 | 7,129 | | 1972 | 6,911 | | 1971 | 6,716 | | 1970 | 6,549 | | 1969 | 6,403 | | 1968 | 6,280 | | 1967 | 6,177 | | 1966 | 6,078 | | 1965 | 5,974 | | 1964 | 5,869 | | 1963 | 5,765 | | 1962 | 5,663 | | 1961 | 5,572 | | 1960 | 5,508 |
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