| Year | Value | | 2022 | 3,448 | | 2021 | 3,419 | | 2020 | 3,330 | | 2019 | 3,221 | | 2018 | 3,124 | | 2017 | 3,081 | | 2016 | 3,101 | | 2015 | 3,187 | | 2014 | 3,317 | | 2013 | 3,453 | | 2012 | 3,551 | | 2011 | 3,578 | | 2010 | 3,485 | | 2009 | 3,337 | | 2008 | 3,241 | | 2007 | 3,202 | | 2006 | 3,214 | | 2005 | 3,251 | | 2004 | 3,260 | | 2003 | 3,233 | | 2002 | 3,195 | | 2001 | 3,167 | | 2000 | 3,095 | | 1999 | 3,029 | | 1998 | 3,014 | | 1997 | 2,989 | | 1996 | 2,948 | | 1995 | 2,870 | | 1994 | 2,752 | | 1993 | 2,618 | | 1992 | 2,494 | | 1991 | 2,214 | | 1990 | 1,886 | | 1989 | 1,774 | | 1988 | 1,841 | | 1987 | 1,999 | | 1986 | 2,170 | | 1985 | 2,339 | | 1984 | 2,515 | | 1983 | 2,700 | | 1982 | 2,892 | | 1981 | 3,107 | | 1980 | 3,297 | | 1979 | 3,425 | | 1978 | 3,531 | | 1977 | 3,629 | | 1976 | 3,703 | | 1975 | 3,706 | | 1974 | 3,640 | | 1973 | 3,566 | | 1972 | 3,478 | | 1971 | 3,406 | | 1970 | 3,374 | | 1969 | 3,353 | | 1968 | 3,336 | | 1967 | 3,316 | | 1966 | 3,266 | | 1965 | 3,194 | | 1964 | 3,129 | | 1963 | 3,053 | | 1962 | 2,960 | | 1961 | 2,860 | | 1960 | 2,727 |
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