Year | Value | 2021 | 18,560 | 2020 | 18,830 | 2019 | 18,850 | 2018 | 18,890 | 2017 | 18,790 | 2016 | 18,860 | 2015 | 18,886 | 2014 | 18,894 | 2013 | 18,934 | 2012 | 19,274 | 2011 | 19,297 | 2010 | 19,447 | 2009 | 19,300 | 2008 | 19,370 | 2007 | 19,300 | 2006 | 19,390 | 2005 | 19,410 | 2004 | 19,340 | 2003 | 22,360 | 2002 | 22,370 | 2001 | 22,550 | 2000 | 24,400 | 1999 | 24,430 | 1998 | 24,430 | 1997 | 24,450 | 1996 | 24,440 | 1995 | 24,460 | 1994 | 24,460 | 1993 | 24,460 | 1992 | 24,460 | 1991 | 24,460 | 1990 | 24,460 | 1989 | 24,460 | 1988 | 24,460 | 1987 | 24,460 | 1986 | 24,460 | 1985 | 24,460 | 1984 | 24,460 | 1983 | 24,460 | 1982 | 24,460 | 1981 | 24,460 | 1980 | 24,460 | 1979 | 24,460 | 1978 | 24,460 | 1977 | 24,460 | 1976 | 24,460 | 1975 | 24,460 | 1974 | 24,460 | 1973 | 24,460 | 1972 | 24,460 | 1971 | 24,460 | 1970 | 24,460 | 1969 | 24,460 | 1968 | 24,460 | 1967 | 24,460 | 1966 | 24,460 | 1965 | 24,460 | 1964 | 24,460 | 1963 | 24,460 | 1962 | 24,460 | 1961 | 24,460 |
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