Year Percent 1999-01-01 12.709600000000000 2000-01-01 15.350400000000000 2001-01-01 14.595999999999998 2002-01-01 13.336100000000000 2003-01-01 18.410800000000000 2004-01-01 20.838600000000000 2005-01-01 23.819300000000000 2006-01-01 30.831600000000000 2007-01-01 31.050200000000000 2008-01-01 16.238700000000000 2009-01-01 23.983200000000000 2010-01-01 25.153500000000000 2011-01-01 18.141500000000000 2012-01-01 24.339600000000000 2013-01-01 28.922900000000000 2014-01-01 27.048600000000000 2015-01-01 29.491200000000000 2016-01-01 30.005700000000000