# year    value 
 1980      0.1 
 1981     0.39 
 1982    -0.19 
 1983     0.18 
 1984     0.29 
 1985     0.02 
 1986    -0.33 
 1987    -0.29 
 1988     0.63 
 1989      0.5 
 1990     0.71 
 1991     0.92 
 1992    -0.38 
 1993      0.6 
 1994     0.48 
 1995     0.64 
 1996    -0.02 
 1997     0.49 
 1998      1.1 
 1999     0.27 
 2000     0.53 
 2001     1.05 
 2002     0.97 
 2003     1.11 
 2004     0.68 
 2005     1.05 
 2006     0.84 
 2007     1.18 
 2008      0.6 
 2009     0.57 
 2010     0.94 
 2011     0.95 
 2012     1.01 
 2013     1.19 
 2014     0.77 
 2015     0.57 
 2016     1.67 
 2017     0.82 
 2018     0.85