Year Percent of GDP 2004-01-01 3.6006 2005-01-01 6.3255 2006-01-01 9.3761 2007-01-01 11.9378 2008-01-01 17.9632 2009-01-01 21.2981 2010-01-01 20.8756 2011-01-01 20.1736 2012-01-01 18.1141 2013-01-01 18.3405 2014-01-01 19.0167 2015-01-01 19.3006 2016-01-01 19.2938 2017-01-01 20.4442