# year    value 
 1980     0.05 
 1981     0.45 
 1982    -0.21 
 1983     0.14 
 1984     0.38 
 1985     0.11 
 1986    -0.36 
 1987    -0.33 
 1988     0.67 
 1989     0.48 
 1990     0.72 
 1991     0.88 
 1992    -0.44 
 1993     0.65 
 1994     0.43 
 1995     0.62 
 1996    -0.03 
 1997     0.31 
 1998     1.19 
 1999     0.25 
 2000     0.61 
 2001     1.08 
 2002     0.96 
 2003     1.12 
 2004     0.61 
 2005     1.08 
 2006     0.83 
 2007     1.15 
 2008     0.61 
 2009     0.56 
 2010     0.89 
 2011     0.96 
 2012      1.1 
 2013     1.21 
 2014     0.74 
 2015     0.51 
 2016     1.69 
 2017     0.77 
 2018     0.82