Year Percent 1960 1.73089 1961 1.99944 1962 2.54211 1963 1.98658 1964 2.09497 1965 1.64951 1966 1.79105 1967 1.78523 1968 0.87717 1969 0.89479 1970 1.35759 1971 1.49375 1972 1.76836 1973 1.95737 1974 2.08529 1975 1.94543 1976 0.88479 1977 0.31136 1978 0.03204 1979 -0.39164 1980 0.12536 1981 0.38475 1982 0.99348 1983 1.35949 1984 0.86519 1985 0.61784 1986 -0.02464 1987 0.86188 1988 0.27448 1989 0.48005 1990 0.92322 1992 1.04174 1993 1.14023 1994 1.32924 1995 1.46436 1996 1.58266 1997 1.31236 1998 0.88728 1999 0.52548 2000 0.58756 2001 0.58929 2002 1.73717 2003 1.97356 2004 1.48622 2005 1.12877 2006 1.21898 2007 0.93241 2008 0.8487 2009 0.99973 2010 1.11173 2011 0.76248 2012 0.54822 2013 0.76835 2014 1.51034 2015 1.88905 2016 2.09936 2017 2.12296