| Year | Value | | 2022 | 24,209 | | 2021 | 23,211 | | 2020 | 22,240 | | 2019 | 21,381 | | 2018 | 20,734 | | 2017 | 20,348 | | 2016 | 20,225 | | 2015 | 20,227 | | 2014 | 20,152 | | 2013 | 20,028 | | 2012 | 19,795 | | 2011 | 19,232 | | 2010 | 18,677 | | 2009 | 18,611 | | 2008 | 19,216 | | 2007 | 20,358 | | 2006 | 21,456 | | 2005 | 22,224 | | 2004 | 22,735 | | 2003 | 22,965 | | 2002 | 22,984 | | 2001 | 23,047 | | 2000 | 23,101 | | 1999 | 22,779 | | 1998 | 21,837 | | 1997 | 20,411 | | 1996 | 18,889 | | 1995 | 17,422 | | 1994 | 16,175 | | 1993 | 15,223 | | 1992 | 14,365 | | 1991 | 13,398 | | 1990 | 12,249 | | 1989 | 10,874 | | 1988 | 9,408 | | 1987 | 8,104 | | 1986 | 7,051 | | 1985 | 6,263 | | 1984 | 5,728 | | 1983 | 5,393 | | 1982 | 5,165 | | 1981 | 4,990 | | 1980 | 4,902 | | 1979 | 4,929 | | 1978 | 5,042 | | 1977 | 5,223 | | 1976 | 5,460 | | 1975 | 5,735 | | 1974 | 6,019 | | 1973 | 6,283 | | 1972 | 6,503 | | 1971 | 6,662 | | 1970 | 6,612 | | 1969 | 6,375 | | 1968 | 6,109 | | 1967 | 5,855 | | 1966 | 5,671 | | 1965 | 5,569 | | 1964 | 5,471 | | 1963 | 5,411 | | 1962 | 5,353 | | 1961 | 5,213 | | 1960 | 5,248 |
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