1979 5.88 1980 3.53 1981 5.72 1982 6.73 1983 3.95 1984 2.60 1985 4.29 1986 1.76 1987 5.72 1988 1.09 1989 3.53 1990 -1.77 1991 2.86 1992 2.02 1993 0.84 1994 1.76 1995 -2.86 1996 1.76 1997 0.17 1998 -0.34 1999 1.76 2000 -1.52 2001 -1.68 2002 -1.68 2003 -1.01 2004 -3.20 2005 -5.05 2006 -6.98 2007 -3.37 2008 -4.46 2009 -3.62 2010 -9.00 2011 -7.57 2012 -8.16 2013 -2.61