| Year | Value | | 2022 | 6,192 | | 2021 | 6,057 | | 2020 | 5,927 | | 2019 | 5,899 | | 2018 | 5,957 | | 2017 | 6,012 | | 2016 | 6,054 | | 2015 | 6,065 | | 2014 | 6,030 | | 2013 | 5,960 | | 2012 | 5,873 | | 2011 | 5,790 | | 2010 | 5,733 | | 2009 | 5,672 | | 2008 | 5,625 | | 2007 | 5,650 | | 2006 | 5,745 | | 2005 | 5,889 | | 2004 | 6,060 | | 2003 | 6,241 | | 2002 | 6,429 | | 2001 | 6,632 | | 2000 | 6,829 | | 1999 | 7,007 | | 1998 | 7,215 | | 1997 | 7,456 | | 1996 | 7,688 | | 1995 | 7,852 | | 1994 | 7,888 | | 1993 | 7,841 | | 1992 | 7,799 | | 1991 | 7,765 | | 1990 | 7,679 | | 1989 | 7,465 | | 1988 | 7,196 | | 1987 | 6,977 | | 1986 | 6,779 | | 1985 | 6,549 | | 1984 | 6,274 | | 1983 | 5,989 | | 1982 | 5,756 | | 1981 | 5,588 | | 1980 | 5,487 | | 1979 | 5,459 | | 1978 | 5,489 | | 1977 | 5,628 | | 1976 | 5,864 | | 1975 | 6,013 | | 1974 | 5,938 | | 1973 | 5,646 | | 1972 | 5,157 | | 1971 | 4,538 | | 1970 | 3,936 | | 1969 | 3,482 | | 1968 | 3,252 | | 1967 | 3,206 | | 1966 | 3,247 | | 1965 | 3,313 | | 1964 | 3,379 | | 1963 | 3,469 | | 1962 | 3,635 | | 1961 | 3,936 | | 1960 | 4,419 |
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