# year    value 
 1980 11.00755 
 1981 11.20746 
 1982 11.19672 
 1983 11.05531 
 1984 10.30992 
 1985 10.83345 
 1986 10.89639 
 1987 11.06123 
 1988 10.74935 
 1989 11.12045 
 1990 10.73982 
 1991 11.26571 
 1992 10.76418 
 1993 10.83762 
 1994 11.03978 
 1995 10.98045 
 1996 11.02584 
 1997 11.22647 
 1998 11.45049 
 1999 11.05801 
 2000 10.75307 
 2001 10.63879 
 2002 10.71592 
 2003 11.26822 
 2004 11.03508 
 2005 10.75453 
 2006 10.70166 
 2007 10.99111 
 2008 10.96322 
 2009 11.70019 
 2010 11.38542 
 2011 11.16064 
 2012 11.16652 
 2013 11.44108 
 2014 11.04875 
 2015 11.92348 
 2016 11.45164 
 2017 11.56439 
 2018 11.61412