# year    value 
 1980     0.44 
 1981     0.89 
 1982     0.46 
 1983    -0.44 
 1984    -0.67 
 1985     -0.2 
 1986     0.37 
 1987     1.53 
 1988     0.95 
 1989     0.56 
 1990     1.36 
 1991     1.01 
 1992     0.61 
 1993     1.06 
 1994     1.04 
 1995     0.75 
 1996      0.3 
 1997      1.2 
 1998      1.2 
 1999      2.5 
 2000     0.72 
 2001     1.61 
 2002     1.69 
 2003     1.23 
 2004     1.49 
 2005     0.55 
 2006     1.29 
 2007     1.68 
 2008     -0.3 
 2009     2.03 
 2010     1.47 
 2011     0.45 
 2012    -0.04 
 2013     1.07 
 2014     0.87 
 2015     1.56 
 2016     1.22 
 2017      2.4 
 2018     1.43