# year    value 
 1980    -0.74 
 1981     0.05 
 1982        1 
 1983     1.31 
 1984     -0.6 
 1985     0.23 
 1986     0.23 
 1987     0.18 
 1988     0.73 
 1989     0.25 
 1990      0.6 
 1991     0.98 
 1992     1.64 
 1993     0.77 
 1994     2.21 
 1995     0.87 
 1996     0.48 
 1997     0.66 
 1998     1.64 
 1999     1.11 
 2000     1.38 
 2001     1.22 
 2002     1.57 
 2003     4.06 
 2004        1 
 2005     0.89 
 2006     1.37 
 2007     1.57 
 2008     1.49 
 2009      1.7 
 2010     1.61 
 2011     1.29 
 2012     2.64 
 2013      1.9 
 2014     0.75 
 2015     3.13 
 2016     1.68 
 2017        3 
 2018     2.68