Year Percent 1997-01-01 4.1597000000000000 1998-01-01 4.1271100000000000 1999-01-01 3.2957800000000000 2000-01-01 2.3374400000000000 2001-01-01 1.4447299999999998 2002-01-01 2.9998900000000000 2003-01-01 2.6966799999999997 2004-01-01 2.2300800000000000 2005-01-01 2.9771099999999997 2006-01-01 2.3060600000000000 2007-01-01 1.9482099999999998 2008-01-01 1.7337900000000002 2009-01-01 2.2666800000000000 2010-01-01 2.0053300000000000 2011-01-01 2.8924300000000000 2012-01-01 4.6867000000000000 2013-01-01 5.1385800000000000 2014-01-01 4.7878000000000000 2015-01-01 7.4216399999999990 2016-01-01 6.8302200000000000