Year Percent 1962 1.40572 1963 0.14349 1964 1.48872 1965 0.12969 1966 2.5335 1967 3.91012 1968 3.31993 1969 5.27097 1970 1.59443 1971 -0.77589 1972 -2.35928 1973 5.03928 1974 1.92382 1975 4.17289 1976 1.43507 1977 3.18274 1978 3.76295 1979 4.56718 1980 4.1055 1981 4.05566 1982 2.60231 1983 3.31919 1984 3.61919 1985 3.51736 1986 2.87462 1987 0.28824 1988 1.05085 1989 0.93303 1990 5.05539 1991 3.3481 1992 3.21712 1993 5.77947 1994 4.60934 1995 4.63992 1996 3.09374 1997 5.80425 1998 4.16736 1999 3.75079 2000 5.36322 2001 -2.22795 2002 3.16693 2003 5.08015 2004 4.58925 2005 5.41454 2006 6.87136 2007 6.03867 2008 5.23275 2009 2.87227 2010 7.35676 2011 7.7822 2012 8.55687 2013 2.59206 2014 4.02081 2015 4.03103 2016 3.30111 2017 1.95372