Year | Value | 2018 | 0.348 | 2016 | 0.353 | 2012 | 0.377 | 2011 | 0.384 | 2010 | 0.392 | 2009 | 0.338 | 2008 | 0.357 | 2007 | 0.36 | 2006 | 0.306 | 2005 | 0.246 | 2004 | 0.385 | 2003 | 0.288 | 2002 | 0.299 | 2001 | 0.29 | 2000 | 0.289 | 1999 | 0.3 | 1998 | 0.256 | 1994 | 0.238 | 1993 | 0.194 | 1989 | 0.194 | 1988 | 0.2 | 1983 | 0.144 | 1981 | 0.134 | 1980 | 0.123 | 1975 | 0.133 | 1970 | 0.064 | 1965 | 0.036 | 1960 | 0.042 |
|