# year    value 
 1980     0.36 
 1981      0.1 
 1982     -0.1 
 1983     0.39 
 1984    -0.12 
 1985    -0.39 
 1986    -0.17 
 1987    -0.12 
 1988     0.44 
 1989     0.62 
 1990     0.69 
 1991     1.13 
 1992    -0.11 
 1993      0.4 
 1994     0.76 
 1995     0.72 
 1996     0.01 
 1997     1.31 
 1998     0.69 
 1999     0.32 
 2000     0.14 
 2001     0.88 
 2002        1 
 2003     1.04 
 2004     0.93 
 2005     0.95 
 2006     0.89 
 2007     1.29 
 2008     0.52 
 2009     0.64 
 2010     1.16 
 2011     0.94 
 2012     0.59 
 2013      1.1 
 2014      0.9 
 2015     0.89 
 2016     1.56 
 2017     1.07 
 2018     1.03