| Year | Value | | 2022 | 19,133 | | 2021 | 18,657 | | 2020 | 18,286 | | 2019 | 18,081 | | 2018 | 18,068 | | 2017 | 18,205 | | 2016 | 18,417 | | 2015 | 18,573 | | 2014 | 18,573 | | 2013 | 18,441 | | 2012 | 18,247 | | 2011 | 18,082 | | 2010 | 18,028 | | 2009 | 18,048 | | 2008 | 18,035 | | 2007 | 17,914 | | 2006 | 17,645 | | 2005 | 17,225 | | 2004 | 16,691 | | 2003 | 16,162 | | 2002 | 15,638 | | 2001 | 15,012 | | 2000 | 14,291 | | 1999 | 13,511 | | 1998 | 12,689 | | 1997 | 11,841 | | 1996 | 10,985 | | 1995 | 10,146 | | 1994 | 9,487 | | 1993 | 9,062 | | 1992 | 8,719 | | 1991 | 8,428 | | 1990 | 8,219 | | 1989 | 8,061 | | 1988 | 7,932 | | 1987 | 7,877 | | 1986 | 7,872 | | 1985 | 7,873 | | 1984 | 7,901 | | 1983 | 7,961 | | 1982 | 8,045 | | 1981 | 8,141 | | 1980 | 8,244 | | 1979 | 8,339 | | 1978 | 8,417 | | 1977 | 8,468 | | 1976 | 8,461 | | 1975 | 8,380 | | 1974 | 8,227 | | 1973 | 8,022 | | 1972 | 7,804 | | 1971 | 7,597 | | 1970 | 7,415 | | 1969 | 7,248 | | 1968 | 7,024 | | 1967 | 6,705 | | 1966 | 6,349 | | 1965 | 6,007 | | 1964 | 5,691 | | 1963 | 5,520 | | 1962 | 5,457 | | 1961 | 5,322 | | 1960 | 5,141 |
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