# year    value 
 1980 0.3103899 
 1981 1.837837 
 1982 -1.730293 
 1983 1.347402 
 1984 -1.382409 
 1985 -1.949076 
 1986  0.22615 
 1987 1.713975 
 1988 -0.5860823 
 1989 -0.848977 
 1990 0.3246506 
 1991 -0.2393124 
 1992 2.563973 
 1993 -1.928938 
 1994 -0.8344963 
 1995 1.567831 
 1996 -0.1804029 
 1997 -0.9109988 
 1998 1.525306 
 1999 1.484982 
 2000 2.255475 
 2001 -1.66301 
 2002  1.27089 
 2003 0.5715961 
 2004 0.2087554 
 2005 1.218503 
 2006 1.857163 
 2007 -0.2129972 
 2008 -0.5326312 
 2009 -0.08644801 
 2010 -1.81784 
 2011 -0.9233621 
 2012 1.604699 
 2013 0.4004051 
 2014 -1.379869 
 2015 1.044889 
 2016 2.204213 
 2017 0.9392921 
 2018 -0.2004452