| Year | Value | | 2022 | 23,608 | | 2021 | 23,027 | | 2020 | 22,431 | | 2019 | 21,889 | | 2018 | 21,401 | | 2017 | 20,967 | | 2016 | 20,578 | | 2015 | 20,223 | | 2014 | 19,892 | | 2013 | 19,567 | | 2012 | 19,233 | | 2011 | 18,877 | | 2010 | 18,496 | | 2009 | 18,124 | | 2008 | 17,792 | | 2007 | 17,509 | | 2006 | 17,294 | | 2005 | 17,162 | | 2004 | 17,000 | | 2003 | 16,711 | | 2002 | 16,317 | | 2001 | 15,821 | | 2000 | 15,218 | | 1999 | 14,561 | | 1998 | 13,919 | | 1997 | 13,291 | | 1996 | 12,661 | | 1995 | 12,031 | | 1994 | 11,401 | | 1993 | 10,803 | | 1992 | 10,234 | | 1991 | 9,663 | | 1990 | 9,108 | | 1989 | 8,614 | | 1988 | 8,180 | | 1987 | 7,814 | | 1986 | 7,546 | | 1985 | 7,346 | | 1984 | 7,193 | | 1983 | 7,066 | | 1982 | 6,950 | | 1981 | 6,842 | | 1980 | 6,742 | | 1979 | 6,619 | | 1978 | 6,463 | | 1977 | 6,294 | | 1976 | 6,115 | | 1975 | 5,943 | | 1974 | 5,799 | | 1973 | 5,686 | | 1972 | 5,596 | | 1971 | 5,527 | | 1970 | 5,448 | | 1969 | 5,340 | | 1968 | 5,216 | | 1967 | 5,086 | | 1966 | 4,955 | | 1965 | 4,829 | | 1964 | 4,710 | | 1963 | 4,603 | | 1962 | 4,507 | | 1961 | 4,420 | | 1960 | 4,340 |
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