Year Percent of GDP 2004-01-01 4.5821 2005-01-01 6.7571 2006-01-01 8.5103 2007-01-01 10.5172 2008-01-01 11.5021 2009-01-01 12.6555 2010-01-01 14.4603 2011-01-01 15.5274 2012-01-01 16.3239 2013-01-01 17.5744 2014-01-01 16.6895 2015-01-01 15.7525 2016-01-01 15.6034 2017-01-01 18.1728