Year Percent 1978 10.52141 1979 -19.1876 1980 13.67052 1981 11.99366 1982 4.41841 1983 3.27284 1984 6.18499 1985 2.06851 1986 7.98392 1987 8.49181 1988 9.5093 1989 0.45696 1990 5.72385 1991 0.72723 1992 1.86331 1993 1.33825 1994 1.19968 1995 1.98186 1996 2.96351 1997 2.05312 1998 5.66958 1999 1.2407 2000 0.70233 2001 0.48176 2002 -1.96985 2003 7.27394 2004 2.83057 2005 -0.43907 2006 2.66803 2007 6.10672 2008 6.93385 2009 -1.38482 2010 0.3752 2011 -0.61775 2012 -1.52115 2013 -1.09636 2014 3.8853 2015 -3.05525 2016 2.10672 2017 -4.7085