| Year | Value | | 2022 | 18,265 | | 2021 | 18,516 | | 2020 | 19,012 | | 2019 | 19,570 | | 2018 | 20,338 | | 2017 | 21,395 | | 2016 | 22,805 | | 2015 | 24,687 | | 2014 | 24,912 | | 2013 | 23,276 | | 2012 | 21,760 | | 2011 | 20,411 | | 2010 | 19,300 | | 2009 | 18,474 | | 2008 | 17,976 | | 2007 | 17,812 | | 2006 | 18,006 | | 2005 | 18,372 | | 2004 | 17,622 | | 2003 | 15,843 | | 2002 | 14,164 | | 2001 | 12,585 | | 2000 | 11,144 | | 1999 | 9,870 | | 1998 | 8,756 | | 1997 | 7,781 | | 1996 | 7,214 | | 1995 | 6,988 | | 1994 | 6,760 | | 1993 | 6,530 | | 1992 | 6,298 | | 1991 | 6,066 | | 1990 | 5,842 | | 1989 | 5,619 | | 1988 | 5,402 | | 1987 | 5,193 | | 1986 | 4,979 | | 1985 | 4,756 | | 1984 | 4,531 | | 1983 | 4,306 | | 1982 | 4,076 | | 1981 | 3,862 | | 1980 | 3,685 | | 1979 | 3,550 | | 1978 | 3,456 | | 1977 | 3,391 | | 1976 | 3,328 | | 1975 | 3,250 | | 1974 | 3,151 | | 1973 | 3,030 | | 1972 | 2,899 | | 1971 | 2,775 | | 1970 | 2,661 | | 1969 | 2,562 | | 1968 | 2,473 | | 1967 | 2,397 | | 1966 | 2,334 | | 1965 | 2,281 | | 1964 | 2,241 | | 1963 | 2,218 | | 1962 | 2,210 | | 1961 | 2,204 | | 1960 | 2,198 |
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