# year    value 
 1980 1.539313 
 1981  1.87075 
 1982 1.511872 
 1983 0.9692842 
 1984 0.2367066 
 1985 0.9655463 
 1986 1.413926 
 1987 2.322404 
 1988 1.997319 
 1989 1.721751 
 1990 2.217961 
 1991 1.741331 
 1992 1.555928 
 1993 2.022435 
 1994 1.657925 
 1995 1.571162 
 1996 1.193966 
 1997 1.799685 
 1998 1.762394 
 1999 3.110332 
 2000 1.585889 
 2001  2.31858 
 2002 2.752571 
 2003  2.08495 
 2004 2.522717 
 2005 1.486696 
 2006 2.302748 
 2007 2.779989 
 2008 0.5920857 
 2009   3.0949 
 2010 2.233192 
 2011 1.389713 
 2012 0.5621831 
 2013 1.730592 
 2014  1.59335 
 2015 2.379463 
 2016 2.409189 
 2017 3.098213 
 2018   2.1053