# year    value 
 1980    -1.25 
 1981     1.09 
 1982    -0.16 
 1983     0.76 
 1984    -1.07 
 1985     0.17 
 1986     0.65 
 1987    -1.38 
 1988     0.48 
 1989     1.51 
 1990     1.44 
 1991    -0.23 
 1992     1.09 
 1993     0.96 
 1994     1.33 
 1995     0.09 
 1996    -0.12 
 1997     0.58 
 1998     0.88 
 1999      1.5 
 2000     2.03 
 2001     1.62 
 2002     1.56 
 2003     1.58 
 2004     0.19 
 2005     0.64 
 2006     0.49 
 2007     2.68 
 2008     1.11 
 2009     2.08 
 2010     0.53 
 2011     2.13 
 2012      1.8 
 2013     0.14 
 2014     1.87 
 2015     1.37 
 2016     1.14 
 2017     2.04 
 2018     2.32