Year | Value | 2021 | 16,030 | 2020 | 16,210 | 2019 | 16,370 | 2018 | 16,520 | 2017 | 16,767 | 2016 | 17,008 | 2015 | 17,360 | 2014 | 17,483 | 2013 | 17,687 | 2012 | 17,880 | 2011 | 17,561 | 2010 | 17,730 | 2009 | 17,950 | 2008 | 18,170 | 2007 | 18,400 | 2006 | 18,580 | 2005 | 18,810 | 2004 | 18,930 | 2003 | 19,020 | 2002 | 19,190 | 2001 | 19,450 | 2000 | 19,730 | 1999 | 19,540 | 1998 | 19,690 | 1997 | 19,830 | 1996 | 20,080 | 1995 | 20,480 | 1994 | 20,960 | 1993 | 21,180 | 1992 | 21,360 | 1991 | 21,610 | 1990 | 21,790 | 1989 | 21,970 | 1988 | 22,140 | 1987 | 22,190 | 1986 | 22,170 | 1985 | 22,200 | 1984 | 22,290 | 1983 | 22,360 | 1982 | 22,430 | 1981 | 22,450 | 1980 | 22,470 | 1979 | 22,520 | 1978 | 22,630 | 1977 | 22,670 | 1976 | 22,700 | 1975 | 22,720 | 1974 | 22,680 | 1973 | 22,710 | 1972 | 22,700 | 1971 | 22,990 | 1970 | 23,240 | 1969 | 23,370 | 1968 | 23,430 | 1967 | 23,360 | 1966 | 23,150 | 1965 | 22,780 | 1964 | 21,910 | 1963 | 21,000 | 1962 | 20,810 | 1961 | 21,130 |
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