Year Percent 1992 0.66125 1993 1.01887 1994 1.51486 1995 2.04719 1996 2.3043 1997 2.98083 1998 3.37567 1999 3.981 2000 3.21582 2001 2.3484 2002 2.04361 2003 2.16604 2004 2.11651 2005 2.00681 2006 2.01642 2007 1.66876 2008 1.60487 2009 1.74969 2010 1.73816 2011 1.69779 2012 1.31392 2013 1.35808 2014 1.25231 2015 1.36455 2016 1.47591 2017 1.37687