# year    value 
 1979 11.62959 
 1980 11.43335 
 1981 11.40154 
 1982 11.91545 
 1983 11.30088 
 1984 11.54834 
 1985  11.5297 
 1986 11.46155 
 1987 11.88836 
 1988 11.64486 
 1989 11.58002 
 1990 11.87731 
 1991 11.56146 
 1992 11.39549 
 1993 11.67778 
 1994 12.31121 
 1995 12.24579 
 1996 11.73253 
 1997  12.4266 
 1998 11.93267 
 1999  11.7136 
 2000 11.70277 
 2001 12.04737 
 2002 12.22136 
 2003  12.4682 
 2004 12.26042 
 2005 11.32301 
 2006 12.37988 
 2007 12.05484 
 2008   12.208 
 2009  12.5399 
 2010 11.94823 
 2011 12.35003 
 2012 12.85548 
 2013 12.04029 
 2014 12.65602 
 2015  12.2332 
 2016 12.42829 
 2017 12.33334 
 2018 12.72059