# year    value 
 1980     0.17 
 1981     0.32 
 1982     0.07 
 1983     0.39 
 1984     0.18 
 1985     0.08 
 1986     0.11 
 1987     0.41 
 1988     0.57 
 1989     0.35 
 1990     0.43 
 1991     0.54 
 1992    -0.04 
 1993     0.31 
 1994     0.38 
 1995     0.66 
 1996     0.39 
 1997     0.54 
 1998     1.07 
 1999     0.62 
 2000     0.52 
 2001     0.75 
 2002     0.77 
 2003     0.78 
 2004     0.53 
 2005     0.91 
 2006      0.9 
 2007     0.74 
 2008     0.68 
 2009     0.76 
 2010     1.07 
 2011      0.9 
 2012     0.99 
 2013     0.85 
 2014     0.91 
 2015     1.06 
 2016     1.27 
 2017     1.11 
 2018     0.96