Year Percent 1999-01-01 0.06 2000-01-01 0.09 2001-01-01 0.13 2002-01-01 0.27 2003-01-01 0.47 2004-01-01 0.67 2005-01-01 0.88 2006-01-01 1.06 2007-01-01 1.37 2008-01-01 2.24 2009-01-01 4.28 2010-01-01 6.58 2011-01-01 6.16 2012-01-01 7.63 2013-01-01 8.43 2014-01-01 9.80 2015-01-01 11.02 2016-01-01 12.71