# year    value 
 1980 1.566907 
 1981 -0.7295517 
 1982 0.1789156 
 1983 1.383051 
 1984 0.5597265 
 1985 -1.255932 
 1986 0.2115055 
 1987 -0.4701939 
 1988 2.555826 
 1989 2.015698 
 1990 2.829073 
 1991 -0.1027934 
 1992 0.851203 
 1993 1.229647 
 1994 2.350042 
 1995  2.47576 
 1996 0.3664802 
 1997 1.328648 
 1998 3.004085 
 1999 0.6028635 
 2000 1.351739 
 2001 2.717877 
 2002 1.276922 
 2003 0.3187403 
 2004 1.234824 
 2005 0.2639147 
 2006 -0.4590771 
 2007 3.982614 
 2008 2.434726 
 2009 0.600338 
 2010 0.3165013 
 2011 0.682646 
 2012 0.667326 
 2013 0.703312 
 2014 3.445596 
 2015 2.158513 
 2016 3.433594 
 2017  1.30786 
 2018  1.59113