# year    value 
 1980     0.06 
 1981     0.38 
 1982    -0.12 
 1983     0.22 
 1984     0.16 
 1985    -0.05 
 1986     0.09 
 1987     0.07 
 1988     0.65 
 1989     0.38 
 1990     0.45 
 1991     0.53 
 1992    -0.39 
 1993    -0.19 
 1994      0.7 
 1995     0.68 
 1996     0.38 
 1997     0.55 
 1998     1.07 
 1999     0.87 
 2000     0.79 
 2001     0.99 
 2002     0.88 
 2003     0.91 
 2004     0.49 
 2005     0.98 
 2006     1.19 
 2007     1.12 
 2008        1 
 2009     0.55 
 2010     1.47 
 2011     1.14 
 2012     1.49 
 2013     1.03 
 2014     0.95 
 2015     1.23 
 2016     1.47 
 2017     1.31 
 2018     1.44