| Year | Value | | 2022 | 24,584 | | 2021 | 23,914 | | 2020 | 23,113 | | 2019 | 22,279 | | 2018 | 21,432 | | 2017 | 20,587 | | 2016 | 19,770 | | 2015 | 18,997 | | 2014 | 18,304 | | 2013 | 17,673 | | 2012 | 17,043 | | 2011 | 16,366 | | 2010 | 15,728 | | 2009 | 15,351 | | 2008 | 15,336 | | 2007 | 15,670 | | 2006 | 16,237 | | 2005 | 16,725 | | 2004 | 16,688 | | 2003 | 15,973 | | 2002 | 14,882 | | 2001 | 13,789 | | 2000 | 12,986 | | 1999 | 12,651 | | 1998 | 12,722 | | 1997 | 12,990 | | 1996 | 13,249 | | 1995 | 13,341 | | 1994 | 13,196 | | 1993 | 12,854 | | 1992 | 12,419 | | 1991 | 11,980 | | 1990 | 11,558 | | 1989 | 11,177 | | 1988 | 10,926 | | 1987 | 10,780 | | 1986 | 10,677 | | 1985 | 10,611 | | 1984 | 10,574 | | 1983 | 10,564 | | 1982 | 10,572 | | 1981 | 10,596 | | 1980 | 10,523 | | 1979 | 10,368 | | 1978 | 10,229 | | 1977 | 10,049 | | 1976 | 9,845 | | 1975 | 9,675 | | 1974 | 9,561 | | 1973 | 9,488 | | 1972 | 9,432 | | 1971 | 9,357 | | 1970 | 9,213 | | 1969 | 9,005 | | 1968 | 8,742 | | 1967 | 8,436 | | 1966 | 8,152 | | 1965 | 7,929 | | 1964 | 7,758 | | 1963 | 7,634 | | 1962 | 7,556 | | 1961 | 7,488 | | 1960 | 7,411 |
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