| Year | Value | | 2022 | 6,371 | | 2021 | 6,327 | | 2020 | 6,298 | | 2019 | 6,226 | | 2018 | 6,053 | | 2017 | 5,864 | | 2016 | 5,731 | | 2015 | 5,595 | | 2014 | 5,477 | | 2013 | 5,442 | | 2012 | 5,456 | | 2011 | 5,544 | | 2010 | 5,682 | | 2009 | 5,819 | | 2008 | 5,964 | | 2007 | 6,083 | | 2006 | 6,166 | | 2005 | 6,224 | | 2004 | 6,291 | | 2003 | 6,338 | | 2002 | 6,327 | | 2001 | 6,269 | | 2000 | 6,152 | | 1999 | 6,006 | | 1998 | 5,864 | | 1997 | 5,755 | | 1996 | 5,665 | | 1995 | 5,558 | | 1994 | 5,453 | | 1993 | 5,367 | | 1992 | 5,272 | | 1991 | 5,212 | | 1990 | 5,221 | | 1989 | 5,276 | | 1988 | 5,362 | | 1987 | 5,465 | | 1986 | 5,515 | | 1985 | 5,405 | | 1984 | 5,168 | | 1983 | 4,879 | | 1982 | 4,554 | | 1981 | 4,255 | | 1980 | 4,058 | | 1979 | 3,981 | | 1978 | 3,991 | | 1977 | 4,050 | | 1976 | 4,124 | | 1975 | 4,174 | | 1974 | 4,175 | | 1973 | 4,125 | | 1972 | 4,034 | | 1971 | 3,913 | | 1970 | 3,800 | | 1969 | 3,710 | | 1968 | 3,621 | | 1967 | 3,560 | | 1966 | 3,552 | | 1965 | 3,563 | | 1964 | 3,598 | | 1963 | 3,660 | | 1962 | 3,711 | | 1961 | 3,725 | | 1960 | 3,707 |
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