Year Percent 2000 0.89166 2001 0.62983 2002 0.50587 2003 0.64053 2004 0.73258 2005 0.82463 2006 0.63214 2007 0.52967 2008 0.40431 2009 0.59216 2010 1.01007 2011 1.29336 2012 2.40234 2013 3.61167 2014 3.97377 2015 3.43838 2016 2.82455 2017 2.20277