Quarter	Billions of US Dollars
1987-01-01	9.077
1987-04-01	9.375
1987-07-01	9.579
1987-10-01	10.194
1988-01-01	10.277
1988-04-01	11.181
1988-07-01	12.256
1988-10-01	13.827
1989-01-01	14.636
1989-04-01	15.002
1989-07-01	15.631
1989-10-01	16.430
1990-01-01	16.428
1990-04-01	16.880
1990-07-01	16.847
1990-10-01	16.558
1991-01-01	15.674
1991-04-01	15.362
1991-07-01	15.296
1991-10-01	15.369
1992-01-01	13.564
1992-04-01	12.641
1992-07-01	12.934
1992-10-01	12.388
1993-01-01	11.383
1993-04-01	10.830
1993-07-01	11.120
1993-10-01	11.048
1994-01-01	10.538
1994-04-01	10.001
1994-07-01	10.521
1994-10-01	10.326
1995-01-01	11.083
1995-04-01	11.528
1995-07-01	11.065
1995-10-01	10.365
1996-01-01	11.503
1996-04-01	12.077
1996-07-01	13.151
1996-10-01	14.759
1997-01-01	15.091
1997-04-01	16.692
1997-07-01	17.192
1997-10-01	17.721
1998-01-01	20.034
1998-04-01	21.361
1998-07-01	21.770
1998-10-01	22.233
1999-01-01	25.434
1999-04-01	27.633
1999-07-01	29.791
1999-10-01	28.529
2000-01-01	27.960
2000-04-01	26.955
2000-07-01	25.283
2000-10-01	26.424
2001-01-01	25.417
2001-04-01	24.592
2001-07-01	25.788
2001-10-01	27.075
2002-01-01	28.856
2002-04-01	27.462
2002-07-01	27.687
2002-10-01	27.546
2003-01-01	29.136
2003-04-01	29.325
2003-07-01	29.032
2003-10-01	29.737
2004-01-01	28.243
2004-04-01	31.357
2004-07-01	32.611
2004-10-01	32.974
2005-01-01	32.146
2005-04-01	30.912
2005-07-01	31.787
2005-10-01	34.439
2006-01-01	39.556
2006-04-01	39.963
2006-07-01	43.859
2006-10-01	48.406
2007-01-01	54.902
2007-04-01	63.975
2007-07-01	64.507
2007-10-01	70.568
2008-01-01	82.728
2008-04-01	101.496
2008-07-01	106.838
2008-10-01	96.499
2009-01-01	90.439
2009-04-01	86.502
2009-07-01	85.015
2009-10-01	81.965
2010-01-01	80.056
2010-04-01	85.638
2010-07-01	95.140
2010-10-01	98.864
2011-01-01	111.033
2011-04-01	109.657
2011-07-01	114.791
2011-10-01	126.210
2012-01-01	142.768
2012-04-01	139.688
2012-07-01	146.262
2012-10-01	154.641
2013-01-01	151.021
2013-04-01	160.800
2013-07-01	188.920
2013-10-01	211.488
2014-01-01	215.597
2014-04-01	232.582
2014-07-01	248.415
2014-10-01	247.956
2015-01-01	253.098
2015-04-01	266.187