Year Percent 1996 2.21022 1997 1.25362 1998 1.13697 1999 0.92439 2000 0.61558 2001 0.74019 2002 1.00053 2003 1.06849 2004 1.37384 2005 3.33918 2006 5.21831 2007 9.15911 2008 8.5201 2009 5.60658 2010 3.90245 2011 3.2476 2012 3.1046 2013 2.7377 2014 2.51758 2015 2.38003 2016 2.44531 2017 2.22514