# year    value 
 1980     0.26 
 1981     -0.1 
 1982     0.19 
 1983    -0.18 
 1984    -0.16 
 1985     0.19 
 1986     0.07 
 1987     0.29 
 1988     0.65 
 1989    -0.27 
 1990     0.33 
 1991     0.63 
 1992     -0.2 
 1993     0.18 
 1994     0.37 
 1995     0.16 
 1996     0.61 
 1997     0.37 
 1998     1.02 
 1999     0.78 
 2000     0.32 
 2001     0.44 
 2002     0.84 
 2003     0.88 
 2004      0.7 
 2005     0.76 
 2006     0.99 
 2007     0.66 
 2008     0.37 
 2009     0.99 
 2010      1.4 
 2011     0.65 
 2012     0.46 
 2013     1.05 
 2014     0.65 
 2015     0.72 
 2016     1.13 
 2017     1.24 
 2018        1