Quarter	Millions of US Dollars
2007-10-01	8797
2008-01-01	15784
2008-04-01	13536
2008-07-01	10832
2008-10-01	7784
2009-01-01	7336
2009-04-01	5188
2009-07-01	6289
2009-10-01	6978
2010-01-01	9817
2010-04-01	8393
2010-07-01	12947
2010-10-01	10727
2011-01-01	10971
2011-04-01	8125
2011-07-01	8251
2011-10-01	8831
2012-01-01	12826
2012-04-01	11579
2012-07-01	12633
2012-10-01	14774
2013-01-01	17120
2013-04-01	15924
2013-07-01	12917
2013-10-01	9769
2014-01-01	8170
2014-04-01	8859
2014-07-01	9031
2014-10-01	8077
2015-01-01	8724
2015-04-01	8012
2015-07-01	8758
2015-10-01	7362
2016-01-01	7361
2016-04-01	7998
2016-07-01	11075
2016-10-01	9933
2017-01-01	13033
2017-04-01	11749
2017-07-01	14494
2017-10-01	13111
2018-01-01	13633