Quarter	Millions of US Dollars
2006-01-01	8219
2006-04-01	13833
2006-07-01	3095
2006-10-01	17989
2007-01-01	3045
2007-04-01	11244
2007-07-01	821
2007-10-01	15422
2008-01-01	7367
2008-04-01	15061
2008-07-01	3818
2008-10-01	14108
2009-01-01	7313
2009-04-01	72778
2009-07-01	8782
2009-10-01	1180
2010-01-01	12357
2010-04-01	11040
2010-07-01	7315
2010-10-01	11287
2011-01-01	18732
2011-04-01	24027
2011-07-01	16221
2011-10-01	14645
2012-01-01	21038
2012-04-01	13916
2012-07-01	17967
2012-10-01	8515
2013-01-01	19864
2013-04-01	17976
2013-07-01	8790
2013-10-01	24339
2014-01-01	18797
2014-04-01	12828
2014-07-01	15909
2014-10-01	15646
2015-01-01	16539
2015-04-01	10111
2015-07-01	7686
2015-10-01	2418
2016-01-01	-1936
2016-04-01	-7805
2016-07-01	12101
2016-10-01	4785
2017-01-01	12016
2017-04-01	14150
2017-07-01	16585
2017-10-01	-2336
2018-01-01	13716