Year Percent 1961 3.50597 1962 1.96728 1963 6.01161 1964 4.87228 1965 7.6107 1966 3.0619 1967 2.64747 1968 4.40548 1969 2.70884 1970 8.3855 1971 -2.21874 1972 -1.90032 1973 4.14193 1974 0.6491 1975 1.22015 1976 2.06122 1977 0.82249 1978 4.72905 1979 0.50053 1980 6.68558 1981 4.40511 1982 3.02787 1983 3.2498 1984 1.61365 1985 4.10306 1986 2.12947 1987 3.10477 1988 4.31897 1989 1.83506 1990 1.46087 1991 2.166 1992 4.8494 1993 -0.85914 1994 1.12167 1995 2.34806 1996 2.25811 1997 -1.44951 1998 0.09508 1999 1.24687 2000 1.91354 2001 -0.23443 2002 1.04604 2003 2.68182 2004 5.17755 2005 5.47816 2006 4.0253 2007 2.71503 2008 -0.3567 2009 0.73564 2010 -0.48466 2011 0.61062 2012 1.33855 2013 2.21269 2014 2.51197 2015 2.61073 2016 3.43865 2017 3.6552