Quarter	Billions of US Dollars
1990-04-01	150
1998-01-01	100
2002-04-01	-150
2007-04-01	150
2008-01-01	-100
2011-04-01	15
2011-07-01	50
2012-04-01	324
2012-07-01	240
2012-10-01	51
2013-01-01	295
2013-04-01	184
2013-07-01	168
2013-10-01	225
2014-01-01	-20
2014-04-01	-84
2014-07-01	-398
2015-04-01	-97
2015-07-01	14
2015-10-01	11
2016-04-01	108
2016-07-01	23
2016-10-01	-11
2017-01-01	124
2017-04-01	85
2017-07-01	-103
2017-10-01	-124
2018-01-01	-500
2018-04-01	-98