Year Percent 1999-01-01 6.691750000000000 2000-01-01 5.708120000000000 2001-01-01 4.897069999999999 2002-01-01 5.351300000000000 2003-01-01 5.541170000000000 2004-01-01 7.756539999999999 2005-01-01 12.691400000000000 2006-01-01 16.920800000000000 2007-01-01 24.267500000000000 2008-01-01 17.683300000000000 2009-01-01 22.336300000000000 2010-01-01 23.807600000000000 2011-01-01 21.178000000000000 2012-01-01 20.152400000000000 2013-01-01 22.015200000000000 2014-01-01 20.511700000000000 2015-01-01 20.315300000000000 2016-01-01 22.576100000000000 2017-01-01 25.428500000000000