# year    value 
 1980      0.8 
 1981    -0.51 
 1982     0.39 
 1983      0.5 
 1984    -0.05 
 1985    -0.22 
 1986    -0.03 
 1987     0.21 
 1988     0.72 
 1989     0.48 
 1990     0.96 
 1991     0.47 
 1992    -0.11 
 1993    -0.22 
 1994     0.58 
 1995     0.91 
 1996     0.22 
 1997      0.5 
 1998     1.42 
 1999     1.04 
 2000     0.23 
 2001     1.25 
 2002     0.79 
 2003     0.74 
 2004     0.91 
 2005     1.28 
 2006     1.71 
 2007     0.93 
 2008     1.19 
 2009     0.71 
 2010     1.28 
 2011        1 
 2012     0.34 
 2013     1.25 
 2014     1.03 
 2015     1.19 
 2016     0.73 
 2017     1.31 
 2018     0.61