Quarter	Millions of US Dollars
1997-10-01	569
1998-01-01	523
1998-04-01	543
1998-07-01	495
1998-10-01	596
1999-01-01	499
1999-04-01	475
1999-07-01	445
1999-10-01	469
2000-01-01	433
2000-04-01	439
2000-07-01	386
2000-10-01	386
2001-01-01	341
2001-04-01	376
2001-07-01	351
2001-10-01	403
2002-01-01	450
2002-04-01	503
2002-07-01	485
2002-10-01	548
2003-01-01	482
2003-04-01	521
2003-07-01	494
2003-10-01	520
2004-01-01	385
2004-04-01	371
2004-07-01	374
2004-10-01	407
2005-01-01	383
2005-04-01	293
2005-07-01	270
2005-10-01	1266
2006-01-01	1565
2006-04-01	1610
2006-07-01	1627
2006-10-01	1698
2007-01-01	1695
2007-04-01	1733
2007-07-01	1792
2007-10-01	1991
2008-01-01	2064
2008-04-01	2091
2008-07-01	1872
2008-10-01	1937
2009-01-01	1741
2009-04-01	1951
2009-07-01	2051
2009-10-01	1805
2010-01-01	1774
2010-04-01	2404
2010-07-01	2762
2010-10-01	2574
2011-01-01	2894
2011-04-01	3007
2011-07-01	2750
2011-10-01	2469
2012-01-01	2795
2012-04-01	2612
2012-07-01	2809
2012-10-01	2994
2013-01-01	2837
2013-04-01	2947
2013-07-01	3103
2013-10-01	2878
2014-01-01	2920
2014-04-01	2843
2014-07-01	2655
2014-10-01	2516
2015-01-01	2266
2015-04-01	2311
2015-07-01	2307
2015-10-01	1369
2016-01-01	1439
2016-04-01	2293
2016-07-01	2444
2016-10-01	2330
2017-01-01	2406
2017-04-01	1655
2017-07-01	2024
2017-10-01	2147
2018-01-01	2290