Year Percent 2005-01-01 0.20 2006-01-01 0.18 2007-01-01 0.16 2008-01-01 0.14 2009-01-01 0.15 2010-01-01 0.16 2011-01-01 0.12 2012-01-01 0.12 2013-01-01 0.11 2014-01-01 0.11 2015-01-01 0.10