# year    value 
 1980 2.909927 
 1981 0.6912286 
 1982 1.430138 
 1983  2.83024 
 1984 1.968319 
 1985 -0.0569145 
 1986 1.567555 
 1987 0.780018 
 1988 3.960307 
 1989 3.341373 
 1990 4.185598 
 1991 1.260917 
 1992  2.22504 
 1993 2.502762 
 1994 3.772391 
 1995 3.894601 
 1996  1.56948 
 1997 2.507577 
 1998 4.401749 
 1999 1.934279 
 2000 2.763838 
 2001  4.12058 
 2002 2.643681 
 2003 1.569678 
 2004 2.591363 
 2005 1.633153 
 2006 0.9066911 
 2007  5.39544 
 2008  3.78699 
 2009 1.993656 
 2010 1.724425 
 2011 1.991425 
 2012 2.091318 
 2013 2.118342 
 2014 4.833761 
 2015 3.564266 
 2016  4.80532 
 2017 2.553034 
 2018 3.049227