| Year | Value | | 2022 | 16,279 | | 2021 | 17,558 | | 2020 | 18,576 | | 2019 | 19,367 | | 2018 | 19,739 | | 2017 | 19,847 | | 2016 | 19,837 | | 2015 | 19,752 | | 2014 | 19,613 | | 2013 | 19,853 | | 2012 | 20,405 | | 2011 | 20,750 | | 2010 | 20,815 | | 2009 | 20,572 | | 2008 | 20,084 | | 2007 | 19,381 | | 2006 | 18,483 | | 2005 | 17,484 | | 2004 | 16,421 | | 2003 | 15,337 | | 2002 | 14,339 | | 2001 | 13,460 | | 2000 | 12,740 | | 1999 | 12,250 | | 1998 | 11,956 | | 1997 | 11,761 | | 1996 | 11,608 | | 1995 | 11,430 | | 1994 | 11,215 | | 1993 | 11,014 | | 1992 | 10,825 | | 1991 | 10,615 | | 1990 | 10,373 | | 1989 | 10,129 | | 1988 | 9,915 | | 1987 | 9,707 | | 1986 | 9,472 | | 1985 | 9,169 | | 1984 | 8,721 | | 1983 | 8,185 | | 1982 | 7,664 | | 1981 | 7,176 | | 1980 | 6,751 | | 1979 | 6,398 | | 1978 | 6,128 | | 1977 | 5,881 | | 1976 | 5,608 | | 1975 | 5,342 | | 1974 | 5,102 | | 1973 | 4,882 | | 1972 | 4,681 | | 1971 | 4,528 | | 1970 | 4,429 | | 1969 | 4,366 | | 1968 | 4,321 | | 1967 | 4,297 | | 1966 | 4,329 | | 1965 | 4,417 | | 1964 | 4,483 | | 1963 | 4,505 | | 1962 | 4,511 | | 1961 | 4,494 | | 1960 | 4,445 |
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