| Year | Value | | 2022 | 18,727 | | 2021 | 19,021 | | 2020 | 19,241 | | 2019 | 18,909 | | 2018 | 18,117 | | 2017 | 17,310 | | 2016 | 16,510 | | 2015 | 15,829 | | 2014 | 15,279 | | 2013 | 14,761 | | 2012 | 14,335 | | 2011 | 14,162 | | 2010 | 14,039 | | 2009 | 13,762 | | 2008 | 13,472 | | 2007 | 13,125 | | 2006 | 12,764 | | 2005 | 12,415 | | 2004 | 12,025 | | 2003 | 11,625 | | 2002 | 11,236 | | 2001 | 10,846 | | 2000 | 10,434 | | 1999 | 10,035 | | 1998 | 9,649 | | 1997 | 9,278 | | 1996 | 8,988 | | 1995 | 8,702 | | 1994 | 8,429 | | 1993 | 8,040 | | 1992 | 8,099 | | 1991 | 9,127 | | 1990 | 9,856 | | 1989 | 9,967 | | 1988 | 10,246 | | 1987 | 10,311 | | 1986 | 9,945 | | 1985 | 9,529 | | 1984 | 9,132 | | 1983 | 8,778 | | 1982 | 8,471 | | 1981 | 8,404 | | 1980 | 8,293 | | 1979 | 7,562 | | 1978 | 6,628 | | 1977 | 6,112 | | 1976 | 5,886 | | 1975 | 5,676 | | 1974 | 5,462 | | 1973 | 5,222 | | 1972 | 4,961 | | 1971 | 4,708 | | 1970 | 4,465 | | 1969 | 4,236 | | 1968 | 4,018 | | 1967 | 3,813 | | 1966 | 3,614 | | 1965 | 3,415 | | 1964 | 3,219 | | 1963 | 3,025 | | 1962 | 2,830 | | 1961 | 2,640 | | 1960 | 2,456 |
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