# year    value 
 1980   0.3725 
 1981 1.439167 
 1982 -0.2258333 
 1983     0.58 
 1984   0.3525 
 1985 0.1191667 
 1986 0.1058333 
 1987 -0.2466667 
 1988    0.855 
 1989 0.6941667 
 1990 0.5791667 
 1991   0.8325 
 1992    -0.02 
 1993 0.8308333 
 1994 0.3466667 
 1995 1.599167 
 1996 0.9266666 
 1997 0.8866666 
 1998     0.74 
 1999 0.5933333 
 2000   1.1275 
 2001 1.056667 
 2002   1.1625 
 2003 1.719167 
 2004 0.6891667 
 2005 2.060833 
 2006    1.295 
 2007 2.113333 
 2008 1.498333 
 2009   0.9475 
 2010   1.6625 
 2011     2.12 
 2012 1.590833 
 2013 1.368333 
 2014 1.721667 
 2015    1.875 
 2016 2.831667 
 2017 2.263333 
 2018 1.795833