Year Percent 1960 3.21942 1961 3.13424 1962 3.07064 1963 3.09174 1964 3.24294 1965 3.41709 1966 3.67757 1967 3.83695 1968 3.63353 1969 2.98066 1970 2.07407 1971 1.09602 1972 0.30545 1973 -0.01284 1974 0.29816 1975 1.06353 1976 1.94784 1977 2.63482 1978 3.15227 1979 3.35546 1980 3.36445 1981 3.3663 1982 3.38357 1983 3.3001 1984 3.12621 1985 2.89615 1986 2.60563 1987 2.32861 1988 2.19849 1989 2.22456 1990 2.35278 1991 2.52973 1992 2.61138 1993 2.45548 1994 2.02206 1995 1.4035 1996 0.72997 1997 0.14573 1998 -0.24361 1999 -0.39064 2000 -0.3568 2001 -0.24884 2002 -0.16998 2003 -0.15622 2004 -0.224 2005 -0.35813 2006 -0.48329 2007 -0.57506 2008 -0.57264 2009 -0.49703 2010 -0.33145 2011 -0.14294 2012 0.03382 2013 0.19208 2014 0.30137 2015 0.40106 2016 0.48145 2017 0.57678