Year | Value | 2021 | 20,310 | 2020 | 20,310 | 2019 | 21,067 | 2018 | 21,828 | 2017 | 22,589 | 2016 | 23,350 | 2015 | 23,350 | 2014 | 23,350 | 2013 | 23,350 | 2012 | 23,072.5 | 2011 | 22,765 | 2010 | 22,200 | 2009 | 21,680 | 2008 | 21,040 | 2007 | 20,630 | 2006 | 20,250 | 2005 | 19,850 | 2004 | 19,460 | 2003 | 19,110 | 2002 | 18,760 | 2001 | 18,410 | 2000 | 18,060 | 1999 | 17,730 | 1998 | 17,650 | 1997 | 17,560 | 1996 | 17,000 | 1995 | 17,000 | 1994 | 16,900 | 1993 | 16,650 | 1992 | 16,640 | 1991 | 16,620 | 1990 | 16,600 | 1989 | 16,520 | 1988 | 16,500 | 1987 | 16,400 | 1986 | 16,380 | 1985 | 16,350 | 1984 | 16,300 | 1983 | 16,200 | 1982 | 16,170 | 1981 | 16,090 | 1980 | 16,060 | 1979 | 16,050 | 1978 | 15,980 | 1977 | 15,900 | 1976 | 15,800 | 1975 | 15,680 | 1974 | 15,550 | 1973 | 15,320 | 1972 | 15,120 | 1971 | 14,820 | 1970 | 14,770 | 1969 | 14,720 | 1968 | 14,700 | 1967 | 14,600 | 1966 | 14,600 | 1965 | 14,500 | 1964 | 14,500 | 1963 | 15,000 | 1962 | 15,500 | 1961 | 15,500 |
|