| Year | Value | | 2021 | 1,231.349 | | 2020 | 1,276.493 | | 2019 | 1,253.284 | | 2018 | 1,324.469 | | 2017 | 1,214.2 | | 2016 | 1,093.9 | | 2015 | 1,266.8 | | 2014 | 1,089.8 | | 2013 | 1,088.3 | | 2012 | 1,169 | | 2011 | 1,163 | | 2010 | 1,145 | | 2009 | 1,276 | | 2008 | 1,156 | | 2007 | 1,472 | | 2006 | 1,570 | | 2005 | 1,670 | | 2004 | 1,560 | | 2003 | 1,540 | | 2002 | 1,400 | | 2001 | 1,400 | | 2000 | 1,415 | | 1999 | 1,442 | | 1998 | 1,442 | | 1997 | 1,422 | | 1996 | 1,432 | | 1995 | 1,431 | | 1994 | 1,434 | | 1993 | 1,587 | | 1992 | 1,596 | | 1991 | 1,592 | | 1990 | 1,606 | | 1989 | 1,614 | | 1988 | 1,614 | | 1987 | 1,624 | | 1986 | 1,632 | | 1985 | 1,628 | | 1984 | 1,820 | | 1983 | 1,830 | | 1982 | 1,820 | | 1981 | 1,759 | | 1980 | 1,715 | | 1979 | 1,725 | | 1978 | 1,743 | | 1977 | 1,761 | | 1976 | 1,779 | | 1975 | 1,803 | | 1974 | 2,870 | | 1973 | 3,942 | | 1972 | 3,940 | | 1971 | 3,960 | | 1970 | 3,980 | | 1969 | 3,990 | | 1968 | 4,010 | | 1967 | 4,010 | | 1966 | 4,000 | | 1965 | 4,020 | | 1964 | 4,030 | | 1963 | 4,050 | | 1962 | 4,020 | | 1961 | 4,040 |
|