Year Percent 1997-01-01 5.03076 1998-01-01 2.38266 1999-01-01 2.85612 2000-01-01 4.23755 2001-01-01 4.60805 2002-01-01 5.42000 2003-01-01 4.61000 2004-01-01 5.07000 2005-01-01 8.36000 2006-01-01 10.59000 2007-01-01 12.66000 2008-01-01 9.48000 2009-01-01 11.79000 2010-01-01 13.89000 2011-01-01 11.67000 2012-01-01 12.05000 2013-01-01 15.47000 2014-01-01 17.05000 2015-01-01 17.37000 2016-01-01 17.18000