# year    value 
 1980     0.26 
 1981     0.11 
 1982     0.08 
 1983     0.44 
 1984     0.17 
 1985     0.16 
 1986     0.14 
 1987      0.6 
 1988     0.55 
 1989     0.21 
 1990     0.44 
 1991      0.4 
 1992     0.19 
 1993      0.3 
 1994     0.46 
 1995     0.72 
 1996     0.42 
 1997      0.9 
 1998     0.76 
 1999     0.33 
 2000     0.46 
 2001     0.39 
 2002     0.77 
 2003     0.68 
 2004      0.7 
 2005     0.76 
 2006     0.76 
 2007     0.74 
 2008     0.75 
 2009     0.96 
 2010     0.68 
 2011     0.64 
 2012     0.97 
 2013     0.86 
 2014     1.05 
 2015     1.27 
 2016     0.84 
 2017     0.97 
 2018     0.99