# year    value 
 1980     0.46 
 1981     0.11 
 1982     0.12 
 1983     0.98 
 1984      0.4 
 1985    -0.03 
 1986     0.38 
 1987     0.58 
 1988     0.39 
 1989     0.82 
 1990     0.54 
 1991     0.29 
 1992     0.48 
 1993      0.2 
 1994     0.16 
 1995      0.7 
 1996     0.45 
 1997     0.27 
 1998     0.98 
 1999      0.5 
 2000     0.31 
 2001     0.55 
 2002     0.56 
 2003     0.72 
 2004     0.65 
 2005     0.72 
 2006     0.55 
 2007     0.81 
 2008     0.33 
 2009     0.57 
 2010     0.78 
 2011     0.44 
 2012     0.69 
 2013     0.82 
 2014     0.87 
 2015     0.56 
 2016     1.42 
 2017     1.16 
 2018     0.75