# year    value 
 1980     0.46 
 1981     1.05 
 1982     -0.1 
 1983     0.09 
 1984     0.59 
 1985    -0.52 
 1986     0.16 
 1987    -0.37 
 1988     0.94 
 1989     1.02 
 1990     2.88 
 1991        1 
 1992     0.25 
 1993     1.27 
 1994     0.82 
 1995     1.92 
 1996     1.38 
 1997     1.87 
 1998     1.05 
 1999      0.3 
 2000     1.88 
 2001     0.73 
 2002     1.47 
 2003     1.88 
 2004     0.72 
 2005     1.88 
 2006     0.86 
 2007     2.15 
 2008     1.46 
 2009     0.98 
 2010     2.42 
 2011      2.9 
 2012     1.58 
 2013     1.04 
 2014     2.83 
 2015     2.55 
 2016     3.45 
 2017     2.62 
 2018     1.19