Year Percent 1974 0.64755 1975 1.66581 1976 1.82443 1977 1.20971 1978 2.55879 1979 1.83564 1980 1.31557 1981 0.9831 1982 1.12561 1983 0.81598 1984 0.60287 1985 0.76853 1986 -0.14051 1987 0.26277 1988 0.24204 1989 0.2166 1990 1.27102 1991 2.72186 1992 2.57514 1993 2.13635 1994 1.46648 1995 2.08968 1996 3.45009 1997 3.31159 1998 12.24958 1999 18.56564 2000 25.53842 2001 8.77137 2002 23.03908 2003 13.64141 2004 -5.67092 2005 22.21984 2006 9.51414 2007 22.20717 2008 8.45704 2009 22.82382 2010 17.01438 2011 9.90087 2012 18.15902 2013 20.86982 2014 33.61718 2015 80.98493 2016 25.97061 2017 -1.02957