Year Percent 1984 3.00142 1985 2.36146 1986 3.66412 1987 3.22069 1988 2.38834 1989 4.19527 1990 3.72328 1991 2.55383 1992 2.95558 1993 1.56191 1994 1.87861 1995 1.58919 1996 1.15695 1997 1.10891 1999 1.792 2004 1.67029 2005 1.84808 2006 1.74414 2007 2.06349 2008 2.08021 2009 1.73164 2010 1.38259 2011 1.26233 2012 1.39367 2013 1.43443 2014 1.66187 2015 1.78555 2016 1.45076 2017 1.34152