# year    value 
 1980     0.19 
 1981      0.3 
 1982     0.06 
 1983     0.35 
 1984     0.13 
 1985     0.07 
 1986     0.13 
 1987     0.36 
 1988     0.53 
 1989     0.33 
 1990     0.43 
 1991     0.52 
 1992    -0.03 
 1993     0.25 
 1994     0.45 
 1995     0.62 
 1996     0.37 
 1997     0.57 
 1998     1.05 
 1999      0.6 
 2000     0.54 
 2001     0.78 
 2002      0.8 
 2003     0.79 
 2004     0.54 
 2005      0.9 
 2006     0.92 
 2007     0.78 
 2008      0.7 
 2009     0.76 
 2010     1.04 
 2011     0.91 
 2012     0.99 
 2013     0.87 
 2014     0.92 
 2015      1.1 
 2016     1.27 
 2017     1.16 
 2018     1.01