| Year | Value | | 2022 | 18,329 | | 2021 | 18,747 | | 2020 | 19,008 | | 2019 | 19,035 | | 2018 | 18,861 | | 2017 | 18,615 | | 2016 | 18,419 | | 2015 | 18,298 | | 2014 | 18,215 | | 2013 | 18,143 | | 2012 | 18,016 | | 2011 | 17,747 | | 2010 | 17,321 | | 2009 | 16,763 | | 2008 | 16,082 | | 2007 | 15,320 | | 2006 | 14,547 | | 2005 | 13,799 | | 2004 | 13,088 | | 2003 | 12,354 | | 2002 | 11,626 | | 2001 | 10,964 | | 2000 | 10,311 | | 1999 | 9,646 | | 1998 | 8,956 | | 1997 | 8,266 | | 1996 | 7,638 | | 1995 | 7,104 | | 1994 | 6,760 | | 1993 | 6,614 | | 1992 | 6,533 | | 1991 | 6,486 | | 1990 | 6,487 | | 1989 | 6,510 | | 1988 | 6,535 | | 1987 | 6,606 | | 1986 | 6,710 | | 1985 | 6,810 | | 1984 | 6,920 | | 1983 | 7,049 | | 1982 | 7,176 | | 1981 | 7,282 | | 1980 | 7,355 | | 1979 | 7,368 | | 1978 | 7,318 | | 1977 | 7,235 | | 1976 | 7,148 | | 1975 | 7,076 | | 1974 | 7,016 | | 1973 | 6,947 | | 1972 | 6,844 | | 1971 | 6,599 | | 1970 | 6,216 | | 1969 | 5,816 | | 1968 | 5,467 | | 1967 | 5,229 | | 1966 | 5,124 | | 1965 | 5,150 | | 1964 | 5,226 | | 1963 | 5,111 | | 1962 | 4,786 | | 1961 | 4,581 | | 1960 | 4,532 |
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