Year Percent 1960 -2.95939 1961 -0.94789 1962 -1.40862 1963 -1.73576 1964 -2.10622 1965 0.40821 1966 -3.47847 1967 -2.84386 1968 -2.96725 1969 -6.22488 1970 -3.14696 1971 -2 1972 -1.57408 1973 -1.21169 1974 -7.46708 1975 -7.46886 1976 -2.33421 1977 3.65864 1978 -4.77441 1979 -12.04306 1980 -22.58031 1981 -16.0767 1982 -18.90103 1983 -15.10267 1984 -5.93967 1985 -11.95319 1986 -11.61115 1987 -10.50411 1988 -10.76033 1989 -9.49657 1990 -7.88231 1991 -10.11374 1992 -9.26301 1993 -9.5455 1994 -11.80502 1995 -10.43979 1996 -8.92729 1997 -7.06132 1998 -6.00735 1999 -7.78407 2000 -10.60504 2001 -6.23622 2002 -6.50847 2003 -6.02924 2004 -8.82114 2005 -8.93023 2006 -11.00412 2007 -10.37651 2008 -13.68607 2009 -6.49241 2010 -7.25925 2011 -13.1909 2012 -11.85912 2013 -8.617 2014 -8.07336 2015 -7.53259 2016 -7.3428 2017 -7.21031