# year    value 
 1979 10.00952 
 1980  9.80402 
 1981 10.36582 
 1982  11.4136 
 1983 10.13432 
 1984 10.56381 
 1985 10.02241 
 1986 10.64913 
 1987 11.77485 
 1988 9.897198 
 1989  9.92909 
 1990 10.47277 
 1991 10.35915 
 1992 10.54991 
 1993 9.360785 
 1994 11.38777 
 1995 10.23767 
 1996 9.751448 
 1997 10.69814 
 1998 9.573849 
 1999 10.78226 
 2000 11.64775 
 2001 10.36225 
 2002 11.10608 
 2003 10.36761 
 2004 11.36659 
 2005 10.96865 
 2006 12.69738 
 2007 9.559229 
 2008 10.71366 
 2009 11.66499 
 2010 10.22529 
 2011 11.56582 
 2012 11.71309 
 2013 11.43211 
 2014 12.51525 
 2015 11.23692 
 2016 11.25736 
 2017  10.6223 
 2018 12.40103