1980 0.135 1981 0.317 1982 -0.002 1983 0.331 1984 -0.045 1985 -0.033 1986 0.120 1987 0.252 1988 0.375 1989 0.245 1990 0.492 1991 0.397 1992 0.093 1993 0.175 1994 0.343 1995 0.592 1996 0.227 1997 0.518 1998 0.835 1999 0.561 2000 0.484 2001 0.681 2002 0.778 2003 0.770 2004 0.674 2005 0.882 2006 0.810 2007 0.909 2008 0.695 2009 0.731 2010 0.901 2011 0.695 2012 0.751 2013 0.791 2014 0.762