Year Percent 1961 1.90061 1962 2.01037 1963 5.14752 1964 1.81222 1965 -0.65607 1966 2.30312 1967 -4.41101 1968 -0.26388 1969 6.91315 1970 1.78343 1971 3.37748 1972 7.29665 1973 2.67786 1974 11.01471 1975 8.17616 1976 6.72551 1977 18.66198 1978 14.53233 1979 7.75353 1980 8.69437 1981 13.58462 1982 9.04652 1983 5.40932 1984 6.50109 1985 0.75707 1986 -6.34568 1987 1.23732 1988 3.40856 1989 4.83162 1990 1.81002 1991 -3.96778 1992 0.22706 1993 -1.44184 1994 14.63896 1995 6.76957 1996 0.34871 1997 1.5562 1998 7.94032 1999 4.43648 2000 -0.81977 2001 3.17963 2002 3.83795 2003 1.48478 2004 0.09063 2005 3.7394 2006 -0.66282 2007 0.99499 2008 7.63919 2009 2.40547 2010 6.8061 2011 6.70595 2012 5.82397 2013 -2.12918 2014 -0.62038 2015 -3.07343 2016 4.02413 2017 3.44276