# year    value 
 1980     0.18 
 1981     1.43 
 1982     -0.2 
 1983     -0.7 
 1984     0.09 
 1985     1.71 
 1986     1.77 
 1987     1.56 
 1988     1.07 
 1989     0.94 
 1990     0.73 
 1991     1.11 
 1992     1.68 
 1993     0.53 
 1994     1.42 
 1995    -0.43 
 1996    -0.16 
 1997     0.02 
 1998     0.42 
 1999     0.53 
 2000     1.92 
 2001     1.03 
 2002    -0.59 
 2003     0.87 
 2004     1.94 
 2005     0.96 
 2006      1.8 
 2007     1.61 
 2008     0.13 
 2009     0.36 
 2010     0.85 
 2011     0.23 
 2012     3.04 
 2013    -0.27 
 2014     0.54 
 2015     1.48 
 2016      1.9 
 2017     1.62 
 2018     1.02