Year Percent 1961 4.10415 1962 5.17605 1963 3.87063 1964 5.12739 1965 3.57498 1966 4.20383 1967 3.85186 1968 3.52582 1969 6.24007 1970 4.75323 1971 4.45179 1972 3.59641 1973 5.35154 1974 3.43749 1975 -1.65576 1976 3.76167 1977 3.03018 1978 3.63154 1979 3.21607 1980 1.20235 1981 0.63216 1982 2.00772 1983 0.71977 1984 0.95908 1985 1.04188 1986 1.74751 1987 1.95293 1988 4.0931 1989 3.73228 1990 2.33341 1991 0.95887 1992 1.09573 1993 -1.04236 1994 1.96513 1995 1.71697 1996 1.02964 1997 1.97595 1998 3.1752 1999 2.87648 2000 3.16612 2001 1.21513 2002 0.38576 2003 0.10747 2004 2.03237 2005 0.84467 2006 1.66366 2007 1.73014 2008 -0.36309 2009 -3.43941 2010 1.46316 2011 1.58671 2012 -0.301 2013 0.05983 2014 0.46439 2015 0.64665 2016 0.78447 2017 1.42668