Year Percent 1960 1.46541 1961 -0.62915 1962 -1.81547 1963 -3.06777 1964 -2.57187 1965 -4.95281 1966 -4.6634 1967 -3.33249 1968 -2.0318 1969 -1.79566 1970 -1.47239 1971 0.2229 1972 -0.40853 1973 -1.36809 1974 -5.22276 1975 -4.23868 1976 -4.84543 1977 -2.56176 1978 0.13053 1979 -0.33125 1980 -2.87295 1981 -2.69368 1982 -2.45029 1983 -1.48142 1984 1.21085 1985 1.00641 1986 1.17187 1987 -0.74485 1988 -1.98273 1989 -4.05464 1990 -4.0425 1991 -3.83866 1992 -3.4821 1993 -1.40536 1994 -0.87842 1995 -0.96661 1996 -0.0916 1997 0.21523 1998 -0.4978 1999 -1.94358 2000 -3.00549 2001 -2.34973 2002 -2.02859 2003 -2.21675 2004 -3.85468 2005 -4.99954 2006 -5.91533 2007 -5.99099 2008 -5.12495 2009 -1.15036 2010 -1.30498 2011 -0.24588 2012 1.46882 2013 3.25546 2014 2.42952 2015 2.26973 2016 3.0172 2017 2.66675