# year    value 
 1960 10.59909 
 1961 10.38393 
 1962 10.76306 
 1963 10.33132 
 1964 10.18759 
 1965 10.35432 
 1966 10.37762 
 1967  10.4742 
 1968 10.59248 
 1969 10.62649 
 1970 10.53213 
 1971 10.21317 
 1972 10.34922 
 1973 10.49252 
 1974 10.32782 
 1975 10.46856 
 1976  10.0779 
 1977 10.68697 
 1978 10.71179 
 1979 10.78819 
 1980  10.7874 
 1981 10.72385 
 1982 10.62592 
 1983  10.7248 
 1984 10.18698 
 1985 10.91612 
 1986 10.65081 
 1987 10.94671 
 1988 10.71186 
 1989 10.90215 
 1990 10.81833 
 1991 10.57287 
 1992 10.35061 
 1993 10.73818 
 1994 10.77443 
 1995 10.56073 
 1996 10.57375 
 1997 10.76199 
 1998 11.19751 
 1999 11.03104 
 2000 10.41176 
 2001 10.72472 
 2002 10.58242 
 2003 10.92606 
 2004 11.02826 
 2005 10.86933 
 2006 10.90189 
 2007  10.6691 
 2008 11.10382 
 2009 11.03736 
 2010 10.86894 
 2011 10.95605 
 2012  10.9626 
 2013 11.26085 
 2014 11.13141 
 2015 11.17611 
 2016 11.41663 
 2017 11.33874 
 2018 11.23333