Quarter	Billions of US Dollars
1968-04-01	0.015
1971-01-01	0.040
1971-04-01	0.040
1971-07-01	0.002
1971-10-01	0.002
1972-01-01	0.096
1972-04-01	0.126
1972-07-01	0.026
1972-10-01	0.060
1973-01-01	0.093
1973-04-01	0.075
1973-10-01	0.013
1974-01-01	0.155
1974-04-01	0.039
1974-07-01	0.233
1974-10-01	0.164
1975-01-01	0.703
1975-04-01	0.597
1975-07-01	0.177
1975-10-01	0.526
1976-01-01	0.862
1976-04-01	0.904
1976-07-01	0.569
1976-10-01	0.678
1977-01-01	0.495
1977-04-01	0.301
1977-07-01	0.227
1977-10-01	0.797
1978-01-01	0.417
1978-04-01	0.518
1978-07-01	0.391
1978-10-01	0.081
1979-01-01	0.524
1979-04-01	0.629
1979-07-01	0.523
1979-10-01	0.489
1980-01-01	0.355
1980-04-01	0.726
1980-07-01	0.496
1980-10-01	1.103
1981-01-01	1.115
1981-04-01	0.764
1981-07-01	0.508
1981-10-01	0.965
1982-01-01	2.631
1982-04-01	1.661
1982-07-01	1.794
1982-10-01	2.888
1983-01-01	1.797
1983-04-01	2.240
1983-07-01	1.720
1983-10-01	1.134
1984-01-01	2.153
1984-04-01	1.195
1984-07-01	2.610
1984-10-01	1.905
1985-01-01	3.416
1985-04-01	3.264
1985-07-01	2.158
1985-10-01	2.468
1986-01-01	2.956
1986-04-01	3.334
1986-07-01	3.915
1986-10-01	2.832
1987-01-01	4.132
1987-04-01	2.336
1987-07-01	1.078
1987-10-01	1.041
1988-01-01	4.687
1988-04-01	4.965
1988-07-01	4.834
1988-10-01	3.900
1989-01-01	4.225
1989-04-01	4.132
1989-07-01	2.341
1989-10-01	2.166
1990-01-01	4.472
1990-04-01	4.567
1990-07-01	3.474
1990-10-01	4.276
1991-01-01	5.113
1991-04-01	6.146
1991-07-01	5.275
1991-10-01	5.715
1992-01-01	7.254
1992-04-01	6.974
1992-07-01	5.580
1992-10-01	6.667
1993-01-01	10.686
1993-04-01	8.683
1993-07-01	8.889
1993-10-01	6.886
1994-01-01	8.542
1994-04-01	5.800
1994-07-01	5.594
1994-10-01	4.170
1995-01-01	4.968
1995-04-01	5.487
1995-07-01	4.606
1995-10-01	6.777
1996-01-01	6.906
1996-04-01	9.626
1996-07-01	6.645
1996-10-01	6.356
1997-01-01	8.952
1997-04-01	9.087
1997-07-01	4.716
1997-10-01	6.040
1998-01-01	12.797
1998-04-01	12.030
1998-07-01	10.024
1998-10-01	13.012
1999-01-01	22.331
1999-04-01	21.158
1999-07-01	13.108
1999-10-01	20.256
2000-01-01	19.485
2000-04-01	24.233
2000-07-01	18.590
2000-10-01	21.139
2001-01-01	42.540
2001-04-01	30.212
2001-07-01	21.688
2001-10-01	39.913
2002-01-01	27.418
2002-04-01	27.576
2002-07-01	21.206
2002-10-01	32.061
2003-01-01	48.094
2003-04-01	56.146
2003-07-01	42.766
2003-10-01	43.814
2004-01-01	47.217
2004-04-01	57.288
2004-07-01	48.545
2004-10-01	60.224
2005-01-01	64.250
2005-04-01	74.747
2005-07-01	34.366
2005-10-01	67.040
2006-01-01	64.573
2006-04-01	73.301
2006-07-01	74.191
2006-10-01	108.453
2007-01-01	78.596
2007-04-01	108.960
2007-07-01	51.967
2007-10-01	80.018
2008-01-01	56.823
2008-04-01	133.555
2008-07-01	72.709
2008-10-01	61.545
2009-01-01	84.113
2009-04-01	160.755
2009-07-01	73.350
2009-10-01	77.322
2010-01-01	88.473
2010-04-01	71.713
2010-07-01	72.854
2010-10-01	85.477
2011-01-01	122.902
2011-04-01	91.090
2011-07-01	53.409
2011-10-01	58.711
2012-01-01	107.448
2012-04-01	63.134
2012-07-01	54.086
2012-10-01	57.408
2013-01-01	77.059
2013-04-01	57.549
2013-07-01	61.034
2013-10-01	78.737
2014-01-01	101.749
2014-04-01	104.754
2014-07-01	65.943
2014-10-01	46.091
2015-01-01	69.062
2015-04-01	45.023