| Year | Value | | 2022 | 29,613 | | 2021 | 28,302 | | 2020 | 27,044 | | 2019 | 25,857 | | 2018 | 24,677 | | 2017 | 23,464 | | 2016 | 22,280 | | 2015 | 21,318 | | 2014 | 20,713 | | 2013 | 20,422 | | 2012 | 20,447 | | 2011 | 20,517 | | 2010 | 20,174 | | 2009 | 19,429 | | 2008 | 18,594 | | 2007 | 17,765 | | 2006 | 16,970 | | 2005 | 16,503 | | 2004 | 16,569 | | 2003 | 17,313 | | 2002 | 18,604 | | 2001 | 19,873 | | 2000 | 20,860 | | 1999 | 21,648 | | 1998 | 22,143 | | 1997 | 22,365 | | 1996 | 22,528 | | 1995 | 22,607 | | 1994 | 22,292 | | 1993 | 21,354 | | 1992 | 20,017 | | 1991 | 18,581 | | 1990 | 17,081 | | 1989 | 15,753 | | 1988 | 14,688 | | 1987 | 13,660 | | 1986 | 12,560 | | 1985 | 11,377 | | 1984 | 10,102 | | 1983 | 8,835 | | 1982 | 7,721 | | 1981 | 6,810 | | 1980 | 6,084 | | 1979 | 5,534 | | 1978 | 5,182 | | 1977 | 5,024 | | 1976 | 5,027 | | 1975 | 5,139 | | 1974 | 5,320 | | 1973 | 5,555 | | 1972 | 5,826 | | 1971 | 6,118 | | 1970 | 6,297 | | 1969 | 6,323 | | 1968 | 6,282 | | 1967 | 6,178 | | 1966 | 6,030 | | 1965 | 5,831 | | 1964 | 5,649 | | 1963 | 5,474 | | 1962 | 5,327 | | 1961 | 5,313 | | 1960 | 5,636 |
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