Quarter	Billions of US Dollars
1987-01-01	6.288
1987-04-01	6.321
1987-07-01	6.149
1987-10-01	6.251
1988-01-01	6.274
1988-04-01	6.242
1988-07-01	6.347
1988-10-01	6.376
1989-01-01	6.806
1989-04-01	6.733
1989-07-01	6.690
1989-10-01	6.477
1990-01-01	6.528
1990-04-01	5.878
1990-07-01	6.490
1990-10-01	6.186
1991-01-01	6.734
1991-04-01	6.296
1991-07-01	6.199
1991-10-01	6.215
1992-01-01	5.487
1992-04-01	5.147
1992-07-01	4.981
1992-10-01	4.727
1993-01-01	4.602
1993-04-01	4.617
1993-07-01	5.868
1993-10-01	6.055
1994-01-01	5.994
1994-04-01	6.147
1994-07-01	6.706
1994-10-01	6.692
1995-01-01	6.967
1995-04-01	7.530
1995-07-01	7.605
1995-10-01	9.189
1996-01-01	6.268
1996-04-01	6.769
1996-07-01	7.601
1996-10-01	8.128
1997-01-01	9.093
1997-04-01	10.297
1997-07-01	10.011
1997-10-01	10.104
1998-01-01	9.890
1998-04-01	9.411
1998-07-01	9.929
1998-10-01	10.509
1999-01-01	12.589
1999-04-01	11.738
1999-07-01	13.934
1999-10-01	14.482
2000-01-01	12.431
2000-04-01	11.433
2000-07-01	11.859
2000-10-01	11.931
2001-01-01	11.728
2001-04-01	11.925
2001-07-01	12.067
2001-10-01	12.099
2002-01-01	13.369
2002-04-01	15.349
2002-07-01	17.197
2002-10-01	17.185
2003-01-01	18.159
2003-04-01	19.617
2003-07-01	19.048
2003-10-01	19.367
2004-01-01	19.661
2004-04-01	20.519
2004-07-01	20.813
2004-10-01	21.669
2005-01-01	22.271
2005-04-01	22.257
2005-07-01	21.882
2005-10-01	19.543
2006-01-01	20.749
2006-04-01	22.172
2006-07-01	22.336
2006-10-01	22.514
2007-01-01	22.258
2007-04-01	22.646
2007-07-01	22.718
2007-10-01	21.842
2008-01-01	21.558
2008-04-01	21.602
2008-07-01	20.819
2008-10-01	20.601
2009-01-01	20.157
2009-04-01	19.108
2009-07-01	18.973
2009-10-01	19.177
2010-01-01	22.108
2010-04-01	22.284
2010-07-01	25.162
2010-10-01	29.656
2011-01-01	31.171
2011-04-01	37.624
2011-07-01	38.632
2011-10-01	43.376
2012-01-01	49.308
2012-04-01	51.695
2012-07-01	57.433
2012-10-01	56.435
2013-01-01	59.186
2013-04-01	65.227
2013-07-01	66.510
2013-10-01	74.104
2014-01-01	79.646
2014-04-01	90.164
2014-07-01	94.594
2014-10-01	95.049
2015-01-01	100.461
2015-04-01	98.492