Year Percent of GDP 2004-01-01 16.3869 2005-01-01 20.4713 2006-01-01 26.5054 2007-01-01 35.3129 2008-01-01 37.6696 2009-01-01 39.0492 2010-01-01 39.1024 2011-01-01 39.3723 2012-01-01 37.8368 2013-01-01 34.1746 2014-01-01 31.5018 2015-01-01 30.4863 2016-01-01 28.7998 2017-01-01 30.4154