# year    value 
 1980     0.27 
 1981      0.2 
 1982     0.01 
 1983    -0.06 
 1984    -0.36 
 1985     0.64 
 1986      0.3 
 1987     0.51 
 1988     0.31 
 1989     0.15 
 1990      0.3 
 1991     0.35 
 1992    -0.09 
 1993     0.42 
 1994     0.41 
 1995    -0.14 
 1996      0.3 
 1997     0.43 
 1998     0.83 
 1999     0.59 
 2000     0.32 
 2001     0.48 
 2002     0.25 
 2003     0.52 
 2004     0.69 
 2005      0.7 
 2006     0.55 
 2007    -0.16 
 2008     0.36 
 2009     0.72 
 2010     0.18 
 2011      0.4 
 2012     0.34 
 2013     0.79 
 2014     0.91 
 2015     0.76 
 2016     0.59 
 2017     0.92 
 2018     0.25