# year    value 
 1980     0.28 
 1981      0.6 
 1982     0.09 
 1983     0.41 
 1984     0.24 
 1985     0.16 
 1986     0.41 
 1987     0.24 
 1988     0.61 
 1989     0.54 
 1990        1 
 1991     0.58 
 1992     0.38 
 1993     0.48 
 1994     0.59 
 1995     0.68 
 1996     0.33 
 1997     0.67 
 1998     1.08 
 1999     0.62 
 2000     1.02 
 2001     0.96 
 2002     0.98 
 2003     0.84 
 2004     0.87 
 2005      1.1 
 2006     0.86 
 2007     1.18 
 2008     1.05 
 2009     0.88 
 2010     1.29 
 2011     0.94 
 2012     1.15 
 2013     0.93 
 2014     1.26 
 2015     1.32 
 2016     1.82 
 2017     1.46 
 2018     1.31