Year Percent 1970 -11.55582 1971 -11.55713 1972 -11.55689 1973 -11.55357 1974 -11.5582 1975 -11.55332 1976 -11.56367 1977 -11.55568 1978 -11.53698 1979 -11.58133 1980 -11.52892 1981 -11.61546 1982 -11.51572 1983 -11.4435 1984 -11.80303 1985 -11.26688 1986 -12.04814 1987 -11.01702 1988 -11.08243 1989 -13.60069 1990 -10.6364 1991 -7.13376 1992 -1.31033 1993 -2.52741 1994 -1.29647 1995 -2.50539 1996 -1.99822 1997 -2.90702 1998 -3.9994 1999 -2.79397 2000 -2.81593 2001 -2.89088 2002 -1.67518 2003 -0.68326 2004 0.73214 2005 2.67401 2006 0.23833 2007 2.70511 2008 -3.78201 2009 2.00548 2010 4.84859 2011 3.24685 2012 5.15579 2013 3.87696 2014 4.89362 2015 2.6968