# year    value 
 1980     -0.2 
 1981     0.84 
 1982     0.12 
 1983      0.5 
 1984     0.07 
 1985     0.19 
 1986     0.66 
 1987     0.12 
 1988     0.55 
 1989     0.77 
 1990     1.34 
 1991     0.71 
 1992     0.29 
 1993      0.4 
 1994     0.68 
 1995     0.82 
 1996    -0.27 
 1997     0.75 
 1998     1.12 
 1999     0.95 
 2000     1.61 
 2001     1.61 
 2002     0.91 
 2003     0.61 
 2004     1.08 
 2005     1.17 
 2006     1.43 
 2007     1.42 
 2008     1.57 
 2009     0.91 
 2010     1.26 
 2011     0.95 
 2012     1.98 
 2013     0.85 
 2014     1.33 
 2015     1.45 
 2016     2.03 
 2017     1.63 
 2018     1.41