| Year | Value | | 2022 | 4,193 | | 2021 | 3,497 | | 2020 | 3,442 | | 2019 | 3,371 | | 2018 | 3,310 | | 2017 | 3,298 | | 2016 | 3,289 | | 2015 | 3,276 | | 2014 | 3,255 | | 2013 | 3,246 | | 2012 | 3,184 | | 2011 | 3,189 | | 2010 | 3,410 | | 2009 | 3,455 | | 2008 | 3,593 | | 2007 | 3,693 | | 2006 | 3,786 | | 2005 | 3,761 | | 2004 | 3,790 | | 2003 | 3,807 | | 2002 | 3,835 | | 2001 | 3,699 | | 2000 | 3,607 | | 1999 | 3,469 | | 1998 | 3,338 | | 1997 | 3,279 | | 1996 | 3,290 | | 1995 | 3,288 | | 1994 | 3,300 | | 1993 | 3,280 | | 1992 | 3,268 | | 1991 | 3,282 | | 1990 | 3,239 | | 1989 | 3,193 | | 1988 | 3,120 | | 1987 | 3,033 | | 1986 | 2,819 | | 1985 | 2,698 | | 1984 | 2,557 | | 1983 | 2,411 | | 1982 | 2,274 | | 1981 | 2,128 | | 1980 | 2,001 | | 1979 | 1,901 | | 1978 | 1,816 | | 1977 | 1,732 | | 1976 | 1,630 | | 1975 | 1,561 | | 1974 | 1,507 | | 1973 | 1,479 | | 1972 | 1,466 | | 1971 | 1,450 | | 1970 | 1,456 | | 1969 | 1,477 | | 1968 | 1,504 | | 1967 | 1,532 | | 1966 | 1,558 | | 1965 | 1,581 | | 1964 | 1,595 | | 1963 | 1,597 | | 1962 | 1,586 | | 1961 | 1,562 | | 1960 | 1,525 |
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