Year Percent 1992 1.58 2000 4.53 2001 3.21 2002 2.77 2003 3.59 2004 3.72 2005 4.5 2006 4.13 2007 3.36 2008 3.16 2009 4.58 2010 5.38 2011 6.82 2012 10.48 2013 13.9 2014 13.86 2015 13.07 2016 11.72 2017 10.45 2018 7.77 2019 6.42 2020 7.08