Year Percent 1960 -28.10046 1961 -21.25921 1962 -1.02477 1963 -12.14083 1964 -4.3557 1965 -3.22913 1966 1.33263 1967 1.80265 1968 -1.05162 1969 -4.28198 1970 -7.07994 1971 -9.22126 1972 -5.27731 1973 -6.0861 1974 3.25927 1975 -9.27666 1976 -4.06409 1977 -11.15375 1978 -14.6329 1979 -1.71745 1980 4 1981 3.70951 1982 1.92678 1983 2.13949 1984 -1.75635 1985 -3.15825 1986 -10.3172 1987 -4.13964 1988 -7.09585 1989 -9.87479 1990 -1.49334 1991 5.51806 1992 1.4501 1993 -1.35506 1994 -3.52299 1995 -2.80145 1996 5.81575 1997 9.56871 1998 0.06226 1999 5.37112 2000 21.28109 2001 14.67245 2002 9.8749 2003 14.37289 2004 14.40503 2005 23.13179 2006 26.89136 2007 22.1982 2008 19.26217 2009 -0.58103 2010 7.02243 2011 10.10163 2012 8.37612 2013 2.80897 2014 -1.70754 2015 -13.36002 2016 -14.26853 2017 -12.30511