# year    value 
 1980      0.6 
 1981     0.62 
 1982     0.53 
 1983      0.7 
 1984     0.47 
 1985     0.22 
 1986     0.23 
 1987     0.75 
 1988     0.47 
 1989     0.64 
 1990     0.63 
 1991     0.58 
 1992    -0.06 
 1993     0.35 
 1994     0.29 
 1995      0.4 
 1996     0.22 
 1997     0.08 
 1998     0.53 
 1999     1.14 
 2000     0.31 
 2001     0.49 
 2002     0.68 
 2003     0.56 
 2004     0.63 
 2005     0.79 
 2006     0.95 
 2007     0.42 
 2008     1.01 
 2009     1.06 
 2010     0.41 
 2011     0.67 
 2012     1.06 
 2013     1.01 
 2014     0.89 
 2015     0.85 
 2016     1.22 
 2017     1.33 
 2018     1.43