# year    value 
 1980     0.53 
 1981      0.3 
 1982     0.01 
 1983     0.39 
 1984     0.36 
 1985     0.23 
 1986     0.21 
 1987     0.47 
 1988     0.73 
 1989     0.09 
 1990     0.24 
 1991     0.48 
 1992     0.17 
 1993      0.2 
 1994     0.42 
 1995     0.45 
 1996     0.42 
 1997      0.2 
 1998     1.11 
 1999     0.62 
 2000     0.61 
 2001     0.74 
 2002     0.96 
 2003     0.88 
 2004     0.88 
 2005     0.92 
 2006     0.72 
 2007     0.81 
 2008     0.74 
 2009     0.81 
 2010     1.49 
 2011     0.69 
 2012     0.77 
 2013     0.98 
 2014      0.9 
 2015     0.98 
 2016     1.57 
 2017     1.12 
 2018     1.14