| Year | Value | | 2022 | 20,148 | | 2021 | 19,847 | | 2020 | 19,597 | | 2019 | 19,321 | | 2018 | 19,013 | | 2017 | 18,747 | | 2016 | 18,556 | | 2015 | 18,444 | | 2014 | 18,400 | | 2013 | 18,412 | | 2012 | 17,941 | | 2011 | 16,893 | | 2010 | 15,722 | | 2009 | 14,505 | | 2008 | 13,272 | | 2007 | 12,486 | | 2006 | 12,184 | | 2005 | 11,901 | | 2004 | 11,627 | | 2003 | 11,350 | | 2002 | 11,080 | | 2001 | 10,822 | | 2000 | 10,546 | | 1999 | 10,245 | | 1998 | 9,965 | | 1997 | 9,699 | | 1996 | 9,471 | | 1995 | 9,273 | | 1994 | 9,026 | | 1993 | 8,739 | | 1992 | 8,419 | | 1991 | 8,122 | | 1990 | 7,884 | | 1989 | 7,678 | | 1988 | 7,479 | | 1987 | 7,263 | | 1986 | 7,056 | | 1985 | 6,854 | | 1984 | 6,654 | | 1983 | 6,460 | | 1982 | 6,270 | | 1981 | 6,084 | | 1980 | 5,899 | | 1979 | 5,717 | | 1978 | 5,538 | | 1977 | 5,363 | | 1976 | 5,193 | | 1975 | 5,029 | | 1974 | 4,877 | | 1973 | 4,732 | | 1972 | 4,593 | | 1971 | 4,455 | | 1970 | 4,314 | | 1969 | 4,164 | | 1968 | 4,012 | | 1967 | 3,857 | | 1966 | 3,698 | | 1965 | 3,541 | | 1964 | 3,385 | | 1963 | 3,230 | | 1962 | 3,078 | | 1961 | 2,930 | | 1960 | 2,784 |
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