| Year | Value | | 2022 | 3,445 | | 2021 | 3,461 | | 2020 | 3,478 | | 2019 | 3,459 | | 2018 | 3,400 | | 2017 | 3,357 | | 2016 | 3,335 | | 2015 | 3,336 | | 2014 | 3,348 | | 2013 | 3,363 | | 2012 | 3,380 | | 2011 | 3,404 | | 2010 | 3,457 | | 2009 | 3,490 | | 2008 | 3,489 | | 2007 | 3,526 | | 2006 | 3,628 | | 2005 | 3,769 | | 2004 | 3,887 | | 2003 | 3,992 | | 2002 | 4,043 | | 2001 | 3,981 | | 2000 | 3,901 | | 1999 | 3,830 | | 1998 | 3,714 | | 1997 | 3,598 | | 1996 | 3,505 | | 1995 | 3,396 | | 1994 | 3,289 | | 1993 | 3,184 | | 1992 | 3,091 | | 1991 | 3,202 | | 1990 | 3,430 | | 1989 | 3,530 | | 1988 | 3,504 | | 1987 | 3,387 | | 1986 | 3,230 | | 1985 | 3,072 | | 1984 | 2,920 | | 1983 | 2,783 | | 1982 | 2,675 | | 1981 | 2,601 | | 1980 | 2,537 | | 1979 | 2,464 | | 1978 | 2,389 | | 1977 | 2,314 | | 1976 | 2,263 | | 1975 | 2,230 | | 1974 | 2,196 | | 1973 | 2,163 | | 1972 | 2,141 | | 1971 | 2,117 | | 1970 | 2,072 | | 1969 | 2,032 | | 1968 | 2,015 | | 1967 | 2,011 | | 1966 | 2,003 | | 1965 | 1,983 | | 1964 | 1,948 | | 1963 | 1,896 | | 1962 | 1,834 | | 1961 | 1,764 | | 1960 | 1,686 |
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