Year Number 2004-01-01 0.0031 2005-01-01 0.0123 2006-01-01 0.0245 2007-01-01 0.0444 2008-01-01 0.0659 2009-01-01 0.1011 2010-01-01 0.1225 2011-01-01 0.1486 2012-01-01 0.1608 2013-01-01 0.1869 2014-01-01 0.2083 2015-01-01 0.2665 2016-01-01 0.3201 2017-01-01 0.3799