Quarter	Millions of US Dollars
1988-04-01	2740
1988-07-01	2548
1988-10-01	2954
1989-01-01	2654
1989-04-01	2504
1989-07-01	2640
1989-10-01	2980
1990-01-01	2926
1990-04-01	3337
1990-07-01	4553
1990-10-01	3977
1991-01-01	3692
1991-04-01	2582
1991-07-01	2762
1991-10-01	1819
1992-01-01	2522
1992-04-01	2876
1992-07-01	2987
1992-10-01	2813
1993-01-01	2944
1993-04-01	2397
1993-07-01	3276
1993-10-01	3389
1994-01-01	3772
1994-04-01	3727
1994-07-01	4081
1994-10-01	5238
1995-01-01	3955
1995-04-01	4352
1995-07-01	4213
1995-10-01	5500
1996-01-01	7038
1996-04-01	8244
1996-07-01	8113
1996-10-01	8363
1997-01-01	7636
1997-04-01	7208
1997-07-01	6677
1997-10-01	7738
1998-01-01	8002
1998-04-01	6665
1998-07-01	6256
1998-10-01	5610
1999-01-01	7120
1999-04-01	7624
1999-07-01	7453
1999-10-01	6819
2000-01-01	7747
2000-04-01	7383
2000-07-01	6092
2000-10-01	7024
2001-01-01	5751
2001-04-01	4946
2001-07-01	4453
2001-10-01	4546
2002-01-01	4991
2002-04-01	5910
2002-07-01	5387
2002-10-01	4958
2003-01-01	5641
2003-04-01	7108
2003-07-01	3628
2003-10-01	4591
2004-01-01	4574
2004-04-01	3918
2004-07-01	4437
2004-10-01	4203
2005-01-01	4551
2005-04-01	4380
2005-07-01	3944
2005-10-01	5525
2006-01-01	6435
2006-04-01	6204
2006-07-01	4780
2006-10-01	4492
2007-01-01	6102
2007-04-01	6771
2007-07-01	4275
2007-10-01	3706
2008-01-01	3554
2008-04-01	3149
2008-07-01	2869
2008-10-01	1426
2009-01-01	1409
2009-04-01	1203
2009-07-01	1326
2009-10-01	1179
2010-01-01	1737
2010-04-01	1235
2010-07-01	1110
2010-10-01	1820
2011-01-01	1507
2011-04-01	1546
2011-07-01	1444
2011-10-01	1366
2012-01-01	1312
2012-04-01	1359
2012-07-01	1703
2012-10-01	1618
2013-01-01	1722
2013-04-01	1268
2013-07-01	1827
2013-10-01	1539
2014-01-01	1772
2014-04-01	1510
2014-07-01	1851
2014-10-01	1606
2015-01-01	1407
2015-04-01	2369
2015-07-01	2613
2015-10-01	2776
2016-01-01	3001
2016-04-01	2888
2016-07-01	2984
2016-10-01	2819
2017-01-01	2814
2017-04-01	2902
2017-07-01	2784
2017-10-01	3118
2018-01-01	3289