Quarter Billions of US Dollars 2011-10-01 0.5 2012-01-01 0.5 2012-04-01 0.5 2012-07-01 0.5 2012-10-01 0.5 2013-01-01 0.5 2013-04-01 0.5 2013-07-01 0.5 2013-10-01 0.5 2014-01-01 0.5 2014-04-01 0.5 2014-07-01 0.5 2014-10-01 0.5 2015-01-01 0.5 2015-04-01 0.5