Year Percent 1997-01-01 0.7861739999999999 1998-01-01 2.7270800000000000 1999-01-01 3.5993300000000000 2000-01-01 8.3622000000000000 2001-01-01 4.9766900000000005 2002-01-01 5.2886400000000000 2003-01-01 5.9658400000000000 2004-01-01 5.7011699999999990 2005-01-01 4.8469100000000000 2006-01-01 4.8454200000000000 2007-01-01 4.1103900000000000 2008-01-01 3.2479299999999998 2009-01-01 4.8297700000000000 2010-01-01 6.5091100000000000 2011-01-01 7.0716600000000005 2012-01-01 9.2949600000000010 2013-01-01 11.1799000000000000 2014-01-01 13.6636000000000000 2015-01-01 2.8239500000000000 2016-01-01 3.7823800000000003