# year    value 
 1980     0.43 
 1981      0.1 
 1982     0.14 
 1983     1.08 
 1984     0.35 
 1985    -0.08 
 1986     0.33 
 1987     0.66 
 1988      0.4 
 1989     0.72 
 1990     0.47 
 1991     0.23 
 1992     0.46 
 1993     0.23 
 1994     0.14 
 1995     0.73 
 1996     0.37 
 1997      0.2 
 1998     1.13 
 1999     0.45 
 2000     0.22 
 2001     0.56 
 2002     0.54 
 2003     0.73 
 2004     0.62 
 2005     0.75 
 2006     0.58 
 2007      0.8 
 2008     0.32 
 2009     0.55 
 2010     0.85 
 2011     0.39 
 2012      0.7 
 2013     0.81 
 2014     0.87 
 2015     0.59 
 2016     1.43 
 2017     1.26 
 2018     0.72