Year Percent 1961 -10.59829 1962 6.06376 1963 5.36605 1964 1.63607 1965 -1.25944 1966 11.01665 1967 -0.018 1968 4.40706 1969 4.32866 1970 -7.91573 1971 17.92915 1972 12.95778 1973 2.12158 1974 0.32062 1975 -2.77585 1976 -1.56878 1977 5.44889 1978 2.98062 1979 3.63118 1980 1.65791 1981 -0.11105 1982 -2.29582 1983 -2.4678 1984 -1.99703 1985 0.51367 1986 3.35193 1987 2.2217 1988 2.55103 1989 1.16762 1990 0.76617 1991 -1.82171 1992 -3.91632 1993 -2.72574 1994 -0.43815 1995 1.35964 1996 1.1821 1997 -2.32335 1998 0.46007 1999 -0.47151 2000 -2.11945 2001 0.98325 2002 -2.15504 2003 0.16744 2004 2.27531 2005 3.04703 2006 3.58809 2007 3.95022 2008 -2.48807 2009 0.51153 2010 5.48794 2011 3.26946 2012 1.78473 2013 3.09107 2014 2.61607 2015 3.00593 2016 3.19238 2017 2.27218