Year | Value | 2019 | 3.891 | 2018 | 3.891 | 2017 | 3.871 | 2016 | 3.849 | 2015 | 3.772 | 2014 | 3.642 | 2013 | 3.605 | 2012 | 3.558 | 2011 | 3.501 | 2010 | 3.588 | 2009 | 3.645 | 2008 | 3.639 | 2007 | 3.61 | 2006 | 3.601 | 2005 | 3.609 | 2004 | 3.612 | 2003 | 3.613 | 2002 | 3.575 | 2001 | 3.471 | 2000 | 3.439 | 1999 | 3.379 | 1998 | 3.314 | 1997 | 3.257 | 1996 | 3.118 | 1995 | 3.022 | 1994 | 2.994 | 1993 | 2.952 | 1992 | 2.951 | 1991 | 2.845 | 1990 | 2.847 | 1989 | 2.8 | 1988 | 2.7 | 1987 | 2.7 | 1986 | 2.6 | 1985 | 2.6 | 1984 | 2.4 | 1983 | 2.3 | 1982 | 2.3 | 1981 | 2.2 | 1980 | 2.1 | 1979 | 2 | 1978 | 2 | 1977 | 1.9 | 1976 | 1.9 | 1975 | 1.8 | 1974 | 1.7 | 1973 | 1.6 | 1972 | 1.6 | 1971 | 1.5 | 1970 | 1.4 | 1969 | 1.3 | 1968 | 1.3 | 1967 | 1.2 | 1966 | 1.2 | 1965 | 1.2 | 1964 | 1.2 | 1963 | 1.2 | 1962 | 1.2 | 1961 | 1.2 | 1960 | 1.2 |
|