# year    value 
 1980    -0.75 
 1981     0.02 
 1982     1.08 
 1983     1.38 
 1984     -0.6 
 1985     0.18 
 1986     0.31 
 1987      0.2 
 1988      0.7 
 1989      0.4 
 1990     0.73 
 1991     0.87 
 1992     1.59 
 1993      0.7 
 1994     2.23 
 1995     0.93 
 1996     0.36 
 1997     0.76 
 1998     1.48 
 1999     1.19 
 2000     1.29 
 2001     1.25 
 2002     1.46 
 2003     4.06 
 2004     0.99 
 2005      0.9 
 2006     1.49 
 2007      1.5 
 2008     1.46 
 2009     1.63 
 2010     1.56 
 2011     1.21 
 2012     2.46 
 2013     1.79 
 2014     0.78 
 2015     2.92 
 2016     1.64 
 2017     2.86 
 2018     2.74