# year    value 
 1980     0.18 
 1981     0.66 
 1982    -0.06 
 1983     -0.1 
 1984     0.19 
 1985        0 
 1986        0 
 1987    -0.01 
 1988    -0.02 
 1989     0.11 
 1990     0.28 
 1991     0.04 
 1992    -0.12 
 1993        0 
 1994     0.52 
 1995     0.18 
 1996    -0.11 
 1997     0.78 
 1998     0.73 
 1999     0.69 
 2000      1.3 
 2001     1.36 
 2002     1.39 
 2003     0.38 
 2004     1.54 
 2005     1.01 
 2006        1 
 2007     1.31 
 2008     1.92 
 2009     1.42 
 2010     0.97 
 2011     0.78 
 2012     1.33 
 2013     1.48 
 2014     1.16 
 2015     1.25 
 2016     1.95 
 2017     1.61 
 2018     2.22