| Year | Value | | 2022 | 21,253 | | 2021 | 21,086 | | 2020 | 20,842 | | 2019 | 20,458 | | 2018 | 19,939 | | 2017 | 19,321 | | 2016 | 18,614 | | 2015 | 17,824 | | 2014 | 16,958 | | 2013 | 16,022 | | 2012 | 15,047 | | 2011 | 14,077 | | 2010 | 13,155 | | 2009 | 12,332 | | 2008 | 11,626 | | 2007 | 11,039 | | 2006 | 10,579 | | 2005 | 10,237 | | 2004 | 9,994 | | 2003 | 9,845 | | 2002 | 9,777 | | 2001 | 9,768 | | 2000 | 9,807 | | 1999 | 9,879 | | 1998 | 9,973 | | 1997 | 10,075 | | 1996 | 10,170 | | 1995 | 10,240 | | 1994 | 10,260 | | 1993 | 10,212 | | 1992 | 10,130 | | 1991 | 10,068 | | 1990 | 9,943 | | 1989 | 9,717 | | 1988 | 9,452 | | 1987 | 9,153 | | 1986 | 8,827 | | 1985 | 8,487 | | 1984 | 8,154 | | 1983 | 7,846 | | 1982 | 7,567 | | 1981 | 7,312 | | 1980 | 7,076 | | 1979 | 6,931 | | 1978 | 7,034 | | 1977 | 7,282 | | 1976 | 7,487 | | 1975 | 7,628 | | 1974 | 7,695 | | 1973 | 7,630 | | 1972 | 7,463 | | 1971 | 7,307 | | 1970 | 7,122 | | 1969 | 6,907 | | 1968 | 6,644 | | 1967 | 6,348 | | 1966 | 6,167 | | 1965 | 6,158 | | 1964 | 6,284 | | 1963 | 6,492 | | 1962 | 6,733 | | 1961 | 6,924 | | 1960 | 6,997 |
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