Year Percent 1960 1.79533 1961 1.94872 1962 1.85337 1963 1.77979 1964 1.77777 1965 1.73268 1966 1.69345 1967 1.61344 1968 1.3677 1969 0.92922 1970 0.52427 1971 0.8087 1972 1.46378 1973 1.50909 1974 1.35292 1975 1.27891 1976 0.99286 1977 0.74443 1978 0.78054 1979 0.97848 1980 1.0589 1981 1.14058 1982 1.33661 1983 1.32404 1984 1.06363 1985 0.78767 1986 0.73259 1987 1.09563 1988 1.56622 1989 1.2384 1990 0.77766 1991 1.15915 1992 1.25663 1993 1.01681 1994 0.86684 1995 0.54247 1996 0.53991 1997 0.8192 1998 1.07086 1999 1.20924 2000 1.36919 2001 1.3293 2002 0.8926 2003 0.6925 2004 0.87794 2005 1.58289 2006 2.34742 2007 2.53009 2008 1.85957 2009 0.34124 2010 -0.1439 2011 0.30547 2012 0.5321 2013 0.94589 2014 1.1125 2015 1.04194 2016 1.38808 2017 1.72749