Year Percent 1961 2.81143 1962 2.65283 1963 2.54222 1964 2.5051 1965 2.51127 1966 2.49288 1967 2.45829 1968 2.42082 1969 2.37888 1970 2.33106 1971 2.02232 1972 2.40971 1973 1.52853 1974 1.82015 1975 2.31182 1976 2.02351 1977 2.09673 1978 0.5874 1979 0.85873 1980 0.91309 1981 1.21608 1982 0.58857 1983 -0.12117 1984 0.59201 1985 0.81102 1986 0.6234 1987 4.24511 1988 0.37303 1989 0.59744 1990 0.49036 1991 1.33196 1992 0.45892 1993 2.08376 1994 2.66577 1995 1.47017 1996 1.46719 1997 1.17345 1998 1.95569 1999 1.9642 2000 0.89266 2001 0.08747 2002 3.05739 2003 -1.13152 2004 -0.37033 2005 0.46331 2006 2.0806 2007 0.51051 2008 2.23628 2009 0.39253 2010 2.79233 2011 -2.62866 2012 0.98098 2013 1.84688 2014 1.5554 2015 2.2298 2016 1.33763 2017 1.22403