Quarter	Millions of US Dollars
1987-10-01	190
1988-01-01	181
1988-04-01	165
1988-07-01	160
1988-10-01	169
1989-01-01	159
1989-04-01	154
1989-07-01	161
1989-10-01	177
1990-01-01	177
1990-04-01	180
1990-07-01	192
1990-10-01	200
1991-01-01	175
1991-04-01	166
1991-07-01	180
1991-10-01	198
1992-01-01	183
1992-04-01	196
1992-07-01	213
1993-07-01	285
1993-10-01	568
1994-01-01	1592
1994-04-01	1603
1994-07-01	2214
1994-10-01	2203
1995-01-01	2332
1995-04-01	2361
1995-07-01	2211
1995-10-01	2560
1996-01-01	2921
1996-04-01	2884
1996-07-01	3865
1996-10-01	3817
1997-01-01	3752
1997-04-01	4123
1997-07-01	4056
1997-10-01	4478
1998-01-01	4450
1998-04-01	4413
1998-07-01	4237
1998-10-01	5377
1999-01-01	5315
1999-04-01	5291
1999-07-01	5135
1999-10-01	5141
2000-01-01	5123
2000-04-01	5109
2000-07-01	5347
2000-10-01	5308
2001-01-01	5223
2001-04-01	6688
2001-07-01	6073
2001-10-01	5974
2002-01-01	5958
2002-04-01	5893
2002-07-01	5866
2002-10-01	5267
2003-01-01	4990
2003-04-01	5011
2003-07-01	5074
2003-10-01	6354
2004-01-01	5335
2004-04-01	5297
2004-07-01	5041
2004-10-01	7046
2005-01-01	6903
2005-04-01	6719
2005-07-01	6437
2005-10-01	6385
2006-01-01	6445
2006-04-01	5867
2006-07-01	5557
2006-10-01	5628
2007-01-01	5649
2007-04-01	5672
2007-07-01	5772
2007-10-01	5850
2008-01-01	6014
2008-04-01	6002
2008-07-01	5797
2008-10-01	4202
2009-01-01	4132
2009-04-01	4218
2009-07-01	4276
2009-10-01	3749
2010-01-01	3655
2010-04-01	3540
2010-07-01	3685
2010-10-01	4871
2011-01-01	4963
2011-04-01	4007
2011-07-01	7066
2011-10-01	7064
2012-01-01	7105
2012-04-01	13049
2012-07-01	14078
2012-10-01	13710
2013-01-01	13686
2013-04-01	13851
2013-07-01	14745
2013-10-01	15219
2014-01-01	14860
2014-04-01	16576
2014-07-01	14741
2014-10-01	15267
2015-01-01	15282
2015-04-01	12847
2015-07-01	12539
2015-10-01	12603
2016-01-01	12663
2016-04-01	12776
2016-07-01	13324
2016-10-01	14834
2017-01-01	14967
2017-04-01	13576
2017-07-01	13833
2017-10-01	16716
2018-01-01	17234
2018-04-01	16476