Year | Value | 2021 | 20,044.6 | 2020 | 19,586 | 2019 | 19,040 | 2018 | 19,490 | 2017 | 20,050 | 2016 | 20,050 | 2015 | 20,070 | 2014 | 20,060 | 2013 | 19,800 | 2012 | 19,590 | 2011 | 19,430 | 2010 | 19,220 | 2009 | 19,060 | 2008 | 18,800 | 2007 | 18,780 | 2006 | 18,840 | 2005 | 18,810 | 2004 | 18,830 | 2003 | 18,860 | 2002 | 18,880 | 2001 | 18,970 | 2000 | 18,260 | 1999 | 17,170 | 1998 | 16,710 | 1997 | 16,510 | 1996 | 16,010 | 1995 | 15,500 | 1994 | 15,500 | 1993 | 17,550 | 1992 | 18,350 | 1991 | 18,750 | 1990 | 18,780 | 1989 | 18,540 | 1988 | 18,530 | 1987 | 18,420 | 1986 | 18,300 | 1985 | 18,190 | 1984 | 18,080 | 1983 | 17,900 | 1982 | 17,750 | 1981 | 17,600 | 1980 | 17,150 | 1979 | 16,970 | 1978 | 16,800 | 1977 | 16,650 | 1976 | 16,390 | 1975 | 16,120 | 1974 | 15,840 | 1973 | 15,050 | 1972 | 15,080 | 1971 | 14,480 | 1970 | 14,040 | 1969 | 13,970 | 1968 | 13,830 | 1967 | 13,750 | 1966 | 13,650 | 1965 | 13,550 | 1964 | 13,450 | 1963 | 13,350 | 1962 | 13,250 | 1961 | 13,150 |
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