| Year | Value | | 2019 | 1,351 | | 2018 | 1,321 | | 2017 | 1,306 | | 2016 | 1,296 | | 2015 | 1,291 | | 2014 | 1,212 | | 2013 | 1,135 | | 2012 | 1,077 | | 2011 | 1,043 | | 2010 | 1,021 | | 2009 | 1,019 | | 2008 | 1,020 | | 2007 | 1,032 | | 2006 | 1,058 | | 2005 | 1,090 | | 2004 | 1,115 | | 2003 | 1,137 | | 2002 | 1,156 | | 2001 | 1,169 | | 2000 | 1,173 | | 1999 | 1,174 | | 1998 | 1,165 | | 1997 | 1,149 | | 1996 | 1,141 | | 1995 | 1,150 | | 1994 | 1,137 | | 1993 | 1,139 | | 1992 | 1,148 | | 1991 | 1,151 | | 1990 | 1,137 | | 1989 | 1,115 | | 1988 | 1,080 | | 1987 | 1,039 | | 1986 | 1,005 | | 1985 | 982 | | 1984 | 999 | | 1983 | 1,011 | | 1982 | 1,011 | | 1981 | 1,000 | | 1980 | 979 | | 1979 | 931 | | 1978 | 881 | | 1977 | 829 | | 1976 | 777 | | 1975 | 732 | | 1974 | 698 | | 1973 | 670 | | 1972 | 651 | | 1971 | 635 | | 1970 | 622 | | 1969 | 629 | | 1968 | 636 | | 1967 | 640 | | 1966 | 639 | | 1965 | 633 | | 1964 | 622 | | 1963 | 608 | | 1962 | 590 | | 1961 | 572 | | 1960 | 555 |
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