| Year | Value | | 2022 | 22,630 | | 2021 | 22,384 | | 2020 | 22,192 | | 2019 | 21,836 | | 2018 | 21,340 | | 2017 | 20,945 | | 2016 | 20,596 | | 2015 | 20,298 | | 2014 | 20,047 | | 2013 | 19,798 | | 2012 | 19,735 | | 2011 | 19,710 | | 2010 | 19,507 | | 2009 | 19,269 | | 2008 | 18,981 | | 2007 | 18,636 | | 2006 | 18,247 | | 2005 | 17,829 | | 2004 | 17,384 | | 2003 | 16,907 | | 2002 | 16,402 | | 2001 | 15,858 | | 2000 | 15,266 | | 1999 | 14,657 | | 1998 | 14,056 | | 1997 | 13,485 | | 1996 | 12,965 | | 1995 | 12,453 | | 1994 | 11,915 | | 1993 | 11,353 | | 1992 | 10,775 | | 1991 | 10,189 | | 1990 | 9,615 | | 1989 | 9,083 | | 1988 | 8,619 | | 1987 | 8,212 | | 1986 | 7,823 | | 1985 | 7,423 | | 1984 | 7,001 | | 1983 | 6,550 | | 1982 | 6,088 | | 1981 | 5,649 | | 1980 | 5,251 | | 1979 | 4,906 | | 1978 | 4,624 | | 1977 | 4,404 | | 1976 | 4,226 | | 1975 | 4,074 | | 1974 | 3,948 | | 1973 | 3,852 | | 1972 | 3,779 | | 1971 | 3,730 | | 1970 | 3,694 | | 1969 | 3,663 | | 1968 | 3,631 | | 1967 | 3,601 | | 1966 | 3,578 | | 1965 | 3,574 | | 1964 | 3,579 | | 1963 | 3,594 | | 1962 | 3,633 | | 1961 | 3,681 | | 1960 | 3,729 |
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