Year Percent 1961 1.7965 1962 0.4717 1963 3.18117 1964 4.35748 1965 2.13071 1966 1.48826 1967 1.76146 1968 3.4798 1969 1.62899 1970 6.17211 1971 3.05305 1972 3.9489 1973 6.30315 1974 -2.5249 1975 -1.47175 1976 2.93538 1977 2.47678 1978 4.19626 1979 3.64841 1980 -2.14479 1981 -0.80554 1982 2.04713 1983 4.18638 1984 2.1145 1985 3.95912 1986 2.88571 1987 5.08288 1988 5.51306 1989 2.30275 1990 0.43113 1991 -1.39196 1992 0.1029 1993 2.28142 1994 3.61591 1995 2.19901 1996 2.2779 1997 3.77064 1998 2.8377 1999 2.87317 2000 3.2944 2001 2.15012 2002 2.02505 2003 2.8459 2004 1.78371 2005 2.39064 2006 1.70566 2007 1.56279 2008 -1.25278 2009 -4.90974 2010 0.90049 2011 0.66268 2012 0.77816 2013 1.3714 2014 2.28081 2015 1.53555 2016 1.21053 2017 1.12929