Quarter	Millions of US Dollars
2008-01-01	51778
2008-04-01	47713
2008-07-01	34729
2008-10-01	41039
2009-01-01	54935
2009-04-01	39004
2009-07-01	64701
2009-10-01	54604
2010-01-01	34731
2010-04-01	18755
2010-07-01	282341
2010-10-01	237423
2011-01-01	259924
2011-04-01	255326
2011-07-01	247022
2011-10-01	249466
2012-01-01	252888
2012-04-01	236206
2012-07-01	259271
2012-10-01	258136
2013-01-01	254254
2013-04-01	240882
2013-07-01	261072
2013-10-01	265521
2014-01-01	271709
2014-04-01	254688
2014-07-01	248712
2014-10-01	237040
2015-01-01	221195
2015-04-01	226610
2015-07-01	228126
2015-10-01	234410
2016-01-01	269281
2016-04-01	250759
2016-07-01	246146
2016-10-01	238637
2017-01-01	262380
2017-04-01	267076
2017-07-01	281704
2017-10-01	294240
2018-01-01	280646