Year Percent 1960 -6.59434 1961 -4.89859 1962 -4.6285 1963 -7.14587 1964 -6.62505 1965 -6.78829 1966 -5.90335 1967 -3.98981 1968 -5.03984 1969 -5.00228 1970 -2.42529 1971 -6.58098 1972 -4.06026 1973 -4.63088 1974 -4.68099 1975 -5.03062 1976 -2.36096 1977 -3.60398 1978 -6.90636 1979 -15.81175 1980 -16.3951 1981 -11.31097 1982 -9.4413 1983 -6.96359 1984 -4.62585 1985 -8.26626 1986 -3.39835 1987 -5.94143 1988 -6.79965 1989 -3.82214 1990 -11.42504 1991 -8.57908 1992 -8.28349 1993 -9.29781 1994 -7.56658 1995 -7.57697 1996 -5.51185 1997 -8.09385 1998 -7.75685 1999 -7.74417 2000 -7.32579 2001 -3.21359 2002 -6.56547 2003 -8.98775 2004 -14.84745 2005 -17.3404 2006 -16.0401 2007 -21.74349 2008 -30.36713 2009 -29.2579 2010 -18.07449 2011 -15.59086 2012 -10.50615 2013 -8.68738 2014 -4.38042 2015 -3.46677 2016 -2.2626 2017 -3.61671