| Year | Value | | 2022 | 22,093 | | 2021 | 23,481 | | 2020 | 24,216 | | 2019 | 24,264 | | 2018 | 24,267 | | 2017 | 24,501 | | 2016 | 24,984 | | 2015 | 25,700 | | 2014 | 26,878 | | 2013 | 28,324 | | 2012 | 29,626 | | 2011 | 30,869 | | 2010 | 31,546 | | 2009 | 30,815 | | 2008 | 28,990 | | 2007 | 26,743 | | 2006 | 24,204 | | 2005 | 21,749 | | 2004 | 19,978 | | 2003 | 18,827 | | 2002 | 17,884 | | 2001 | 17,093 | | 2000 | 16,369 | | 1999 | 15,672 | | 1998 | 15,274 | | 1997 | 15,374 | | 1996 | 15,947 | | 1995 | 16,898 | | 1994 | 18,003 | | 1993 | 18,943 | | 1992 | 19,531 | | 1991 | 19,412 | | 1990 | 18,704 | | 1989 | 18,121 | | 1988 | 18,005 | | 1987 | 18,160 | | 1986 | 18,192 | | 1985 | 17,976 | | 1984 | 17,613 | | 1983 | 17,171 | | 1982 | 16,679 | | 1981 | 16,215 | | 1980 | 16,071 | | 1979 | 16,177 | | 1978 | 16,234 | | 1977 | 16,244 | | 1976 | 16,137 | | 1975 | 15,784 | | 1974 | 15,080 | | 1973 | 14,005 | | 1972 | 12,619 | | 1971 | 11,051 | | 1970 | 9,493 | | 1969 | 8,181 | | 1968 | 7,176 | | 1967 | 6,367 | | 1966 | 5,714 | | 1965 | 5,272 | | 1964 | 4,960 | | 1963 | 4,761 | | 1962 | 4,741 | | 1961 | 4,804 | | 1960 | 5,066 |
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