Year Percent 1990 1.4768 1991 2.98945 1992 3.36883 1993 3.10972 1994 2.50355 1995 1.5848 1996 1.32163 1997 1.44026 1998 1.66611 1999 1.58355 2000 1.24077 2001 0.94957 2002 0.82363 2003 0.65968 2004 0.46527 2005 0.43934 2006 0.40468 2007 0.3036 2008 0.33359 2009 0.74937 2010 0.93207 2011 1.02746 2012 1.0704 2013 0.9097 2014 0.85518 2015 0.8462 2016 0.89009 2017 0.89887