Year Percent 1999-01-01 1.71 2000-01-01 1.55 2001-01-01 1.76 2002-01-01 2.17 2003-01-01 2.21 2004-01-01 2.13 2005-01-01 2.08 2006-01-01 2.26 2007-01-01 2.61 2008-01-01 2.63 2009-01-01 3.08 2010-01-01 3.18 2011-01-01 3.09 2012-01-01 3.15 2013-01-01 3.47 2014-01-01 5.08 2015-01-01 9.55 2016-01-01 7.52