Year Percent 1999 1.36 2000 1.68 2001 1.66 2002 1.92 2006 2.1 2007 2.25 2008 1.76 2009 2.01 2011 1.83 2012 1.49 2013 1.58 2014 1.54 2015 1.42 2016 1.58