Year Percent 1999-01-01 1.2070400000000000 2000-01-01 1.4978200000000002 2001-01-01 4.0356000000000000 2002-01-01 13.5560000000000000 2003-01-01 15.1432000000000000 2004-01-01 16.7024000000000000 2005-01-01 17.6690000000000000 2006-01-01 19.3224000000000000 2007-01-01 17.5383000000000000 2008-01-01 16.7300000000000000 2009-01-01 20.9951000000000000 2010-01-01 19.3641000000000000 2011-01-01 17.2950000000000000 2012-01-01 20.3220000000000000 2013-01-01 19.8748000000000000 2014-01-01 22.6506000000000000 2015-01-01 22.5453000000000000 2016-01-01 22.2590000000000000