# year    value 
 1980     0.26 
 1981    -0.05 
 1982     0.19 
 1983    -0.23 
 1984     -0.2 
 1985     0.18 
 1986     0.08 
 1987     0.33 
 1988     0.64 
 1989    -0.22 
 1990     0.32 
 1991     0.64 
 1992    -0.22 
 1993     0.18 
 1994     0.42 
 1995     0.21 
 1996     0.58 
 1997     0.35 
 1998     1.01 
 1999     0.85 
 2000     0.32 
 2001      0.5 
 2002     0.86 
 2003      0.9 
 2004      0.7 
 2005     0.75 
 2006     1.01 
 2007     0.65 
 2008     0.36 
 2009     1.01 
 2010     1.36 
 2011     0.61 
 2012     0.44 
 2013     1.07 
 2014     0.61 
 2015     0.74 
 2016      1.1 
 2017      1.3 
 2018     1.01