# year    value 
 1960  10.8455 
 1961 11.10714 
 1962 11.23132 
 1963 11.82381 
 1964 11.02069 
 1965 10.81417 
 1966 10.73637 
 1967  11.1049 
 1968 10.81574 
 1969  10.8477 
 1970  10.8247 
 1971 10.86171 
 1972 10.61958 
 1973 11.20405 
 1974  11.3512 
 1975 10.61841 
 1976  11.2058 
 1977 11.69905 
 1978 10.49084 
 1979 10.36303 
 1980 11.62387 
 1981 12.19759 
 1982 10.49554 
 1983 11.10745 
 1984 11.21606 
 1985 10.50138 
 1986 11.89515 
 1987 12.08599 
 1988 11.68657 
 1989 10.96121 
 1990 11.84579 
 1991 11.71499 
 1992  11.6024 
 1993 10.51996 
 1994 11.72975 
 1995 11.51645 
 1996 10.83729 
 1997 11.03436 
 1998 12.08652 
 1999 12.03874 
 2000 11.64787 
 2001 11.87912 
 2002 11.41469 
 2003 11.77476 
 2004 11.60724 
 2005 12.06469 
 2006 12.54693 
 2007 11.83452 
 2008 11.19254 
 2009  11.1801 
 2010 11.59561 
 2011 11.66252 
 2012 13.01069 
 2013  11.2618 
 2014 11.50355 
 2015 12.55106 
 2016 12.86595 
 2017 12.38318 
 2018 11.72251