# year    value 
 1980     0.57 
 1981     0.33 
 1982     0.14 
 1983     0.74 
 1984     0.23 
 1985     0.35 
 1986     0.56 
 1987     0.62 
 1988     0.67 
 1989     0.24 
 1990     0.62 
 1991     0.53 
 1992     0.77 
 1993     0.52 
 1994     0.38 
 1995     0.42 
 1996     0.42 
 1997     0.19 
 1998     1.14 
 1999     0.45 
 2000      0.2 
 2001     0.44 
 2002     0.94 
 2003      0.7 
 2004     0.53 
 2005     0.99 
 2006     0.39 
 2007     0.73 
 2008     0.19 
 2009     0.68 
 2010     1.04 
 2011     0.34 
 2012     0.46 
 2013     0.74 
 2014     0.75 
 2015     0.85 
 2016     1.28 
 2017     0.98 
 2018     0.95