Year | Value | 2021 | 24,330 | 2020 | 24,330 | 2019 | 24,330 | 2018 | 24,333 | 2017 | 24,180 | 2016 | 23,560 | 2015 | 22,230 | 2014 | 22,763 | 2013 | 22,521 | 2012 | 22,853 | 2011 | 23,120 | 2010 | 23,260 | 2009 | 23,390 | 2008 | 23,620 | 2007 | 23,290 | 2006 | 23,070 | 2005 | 23,270 | 2004 | 23,140 | 2003 | 23,040 | 2002 | 23,040 | 2001 | 23,340 | 2000 | 23,340 | 1999 | 23,290 | 1998 | 23,290 | 1997 | 23,290 | 1996 | 23,260 | 1995 | 23,240 | 1994 | 23,290 | 1993 | 23,340 | 1992 | 23,360 | 1991 | 23,230 | 1990 | 23,210 | 1989 | 23,050 | 1988 | 23,430 | 1987 | 23,300 | 1986 | 22,910 | 1985 | 23,080 | 1984 | 23,010 | 1983 | 22,870 | 1982 | 22,920 | 1981 | 23,020 | 1980 | 22,960 | 1979 | 23,090 | 1978 | 22,930 | 1977 | 22,920 | 1976 | 23,590 | 1975 | 23,760 | 1974 | 23,590 | 1973 | 23,590 | 1972 | 23,590 | 1971 | 23,640 | 1970 | 24,270 | 1969 | 24,780 | 1968 | 25,330 | 1967 | 25,830 | 1966 | 25,830 | 1965 | 25,780 | 1964 | 25,780 | 1963 | 25,760 | 1962 | 25,760 | 1961 | 25,810 |
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