# year    value 
 1980     0.15 
 1981     0.21 
 1982     0.23 
 1983     0.67 
 1984     -0.1 
 1985     -0.3 
 1986    -0.31 
 1987    -0.13 
 1988     0.25 
 1989      0.3 
 1990     0.84 
 1991     0.43 
 1992    -0.14 
 1993    -1.03 
 1994     1.03 
 1995     0.56 
 1996    -0.17 
 1997     0.44 
 1998      0.6 
 1999     0.85 
 2000     0.15 
 2001     1.06 
 2002      0.5 
 2003     0.86 
 2004     1.25 
 2005     1.52 
 2006      1.1 
 2007     0.94 
 2008     1.05 
 2009     0.99 
 2010     1.29 
 2011     1.06 
 2012     1.05 
 2013     1.27 
 2014     0.65 
 2015     1.28 
 2016     0.91 
 2017     1.09 
 2018     0.75