Year Percent 1992 0.27048 1993 0.30465 1994 0.30257 1995 0.55378 1996 1.16926 1997 1.24226 1998 1.77398 1999 1.57058 2000 1.9033 2001 2.0837 2002 1.63471 2003 2.84045 2004 2.64322 2005 9.0641 2006 5.20078 2007 7.14201 2008 5.9447 2009 4.06815 2010 4.74292 2011 4.41715 2012 4.65066 2013 2.45977 2014 0.63444 2015 3.35051 2016 3.68927 2017 2.52064