Year Percent of GDP 2004-01-01 15.7672 2005-01-01 18.0528 2006-01-01 20.4393 2007-01-01 22.9145 2008-01-01 20.4116 2009-01-01 22.8550 2010-01-01 25.5830 2011-01-01 26.9035 2012-01-01 29.2262 2013-01-01 31.2750 2014-01-01 33.1157 2015-01-01 34.5859 2016-01-01 36.4119 2017-01-01 38.4952