# year    value 
 1980    -0.02 
 1981     1.25 
 1982    -0.98 
 1983     0.94 
 1984    -0.25 
 1985     0.73 
 1986     0.17 
 1987    -0.17 
 1988     0.34 
 1989    -0.16 
 1990    -0.53 
 1991     1.05 
 1992    -1.33 
 1993     0.06 
 1994     0.37 
 1995     1.28 
 1996     0.79 
 1997     1.13 
 1998     0.25 
 1999     0.73 
 2000     0.75 
 2001     1.17 
 2002     1.15 
 2003     1.73 
 2004     1.16 
 2005     2.73 
 2006     1.38 
 2007     2.27 
 2008     1.72 
 2009     1.42 
 2010     2.41 
 2011     2.19 
 2012     1.89 
 2013     1.56 
 2014     1.11 
 2015      1.7 
 2016     2.47 
 2017     1.99 
 2018     2.14