Quarter	Billions of US Dollars
1987-01-01	8.790
1987-04-01	8.919
1987-07-01	9.067
1987-10-01	9.634
1988-01-01	9.667
1988-04-01	10.123
1988-07-01	11.017
1988-10-01	12.228
1989-01-01	12.858
1989-04-01	13.071
1989-07-01	13.060
1989-10-01	13.657
1990-01-01	13.561
1990-04-01	13.604
1990-07-01	13.382
1990-10-01	13.206
1991-01-01	12.455
1991-04-01	12.164
1991-07-01	12.348
1991-10-01	12.677
1992-01-01	11.173
1992-04-01	10.453
1992-07-01	10.967
1992-10-01	10.555
1993-01-01	9.747
1993-04-01	9.619
1993-07-01	9.537
1993-10-01	9.107
1994-01-01	8.690
1994-04-01	8.507
1994-07-01	9.144
1994-10-01	8.979
1995-01-01	9.632
1995-04-01	10.203
1995-07-01	9.846
1995-10-01	9.124
1996-01-01	9.711
1996-04-01	10.378
1996-07-01	11.323
1996-10-01	13.021
1997-01-01	13.549
1997-04-01	14.202
1997-07-01	14.427
1997-10-01	14.507
1998-01-01	15.650
1998-04-01	16.999
1998-07-01	17.160
1998-10-01	17.360
1999-01-01	19.294
1999-04-01	20.831
1999-07-01	21.668
1999-10-01	20.784
2000-01-01	20.404
2000-04-01	19.865
2000-07-01	18.175
2000-10-01	18.695
2001-01-01	18.142
2001-04-01	17.205
2001-07-01	18.150
2001-10-01	18.349
2002-01-01	19.118
2002-04-01	17.780
2002-07-01	18.088
2002-10-01	17.410
2003-01-01	18.638
2003-04-01	19.675
2003-07-01	19.913
2003-10-01	20.310
2004-01-01	19.384
2004-04-01	21.845
2004-07-01	23.174
2004-10-01	23.356
2005-01-01	22.322
2005-04-01	21.754
2005-07-01	21.769
2005-10-01	23.127
2006-01-01	25.648
2006-04-01	25.799
2006-07-01	27.775
2006-10-01	29.397
2007-01-01	32.535
2007-04-01	36.838
2007-07-01	38.622
2007-10-01	44.978
2008-01-01	52.846
2008-04-01	69.683
2008-07-01	75.178
2008-10-01	67.847
2009-01-01	63.203
2009-04-01	56.281
2009-07-01	57.022
2009-10-01	53.271
2010-01-01	53.806
2010-04-01	61.759
2010-07-01	70.410
2010-10-01	77.618
2011-01-01	90.239
2011-04-01	89.491
2011-07-01	99.475
2011-10-01	112.970
2012-01-01	129.744
2012-04-01	129.697
2012-07-01	137.662
2012-10-01	144.947
2013-01-01	142.029
2013-04-01	150.820
2013-07-01	175.086
2013-10-01	191.261
2014-01-01	198.544
2014-04-01	212.851
2014-07-01	229.910
2014-10-01	229.887
2015-01-01	237.343
2015-04-01	248.142