Year Percent 1998-01-01 2.2351600000000000 1999-01-01 1.9831599999999998 2000-01-01 2.1445200000000000 2001-01-01 2.8757200000000003 2002-01-01 3.2760800000000000 2003-01-01 3.7717300000000002 2004-01-01 3.8540400000000004 2005-01-01 4.4637500000000000 2006-01-01 5.8299100000000000 2007-01-01 10.3236000000000000 2008-01-01 10.9010000000000000 2009-01-01 8.7600900000000000 2010-01-01 8.8969899999999990 2011-01-01 9.5913600000000000 2012-01-01 9.5572699999999990 2013-01-01 9.8951500000000000 2014-01-01 10.2591000000000000 2015-01-01 11.3654000000000000 2016-01-01 12.0169000000000000