Quarter	Millions of US Dollars
1988-04-01	15197
1988-07-01	16700
1988-10-01	19409
1989-01-01	18978
1989-04-01	18154
1989-07-01	20033
1989-10-01	21809
1990-01-01	21909
1990-04-01	24113
1990-07-01	25750
1990-10-01	25903
1991-01-01	26541
1991-04-01	27719
1991-07-01	28401
1991-10-01	28988
1992-01-01	29321
1992-04-01	29140
1992-07-01	26734
1992-10-01	25536
1993-01-01	25472
1993-04-01	23523
1993-07-01	20536
1993-10-01	22039
1994-01-01	22384
1994-04-01	24323
1994-07-01	24161
1994-10-01	25571
1995-01-01	24652
1995-04-01	24308
1995-07-01	26295
1995-10-01	27346
1996-01-01	28968
1996-04-01	30205
1996-07-01	32213
1996-10-01	34612
1997-01-01	33572
1997-04-01	33481
1997-07-01	35449
1997-10-01	31050
1998-01-01	32214
1998-04-01	31943
1998-07-01	32874
1998-10-01	34065
1999-01-01	36216
1999-04-01	39321
1999-07-01	38501
1999-10-01	40289
2000-01-01	39059
2000-04-01	37231
2000-07-01	36148
2000-10-01	37312
2001-01-01	34414
2001-04-01	37398
2001-07-01	38130
2001-10-01	40761
2002-01-01	44500
2002-04-01	47960
2002-07-01	49784
2002-10-01	48982
2003-01-01	53084
2003-04-01	60245
2003-07-01	63302
2003-10-01	76083
2004-01-01	80822
2004-04-01	77021
2004-07-01	84467
2004-10-01	94586
2005-01-01	105108
2005-04-01	111895
2005-07-01	115890
2005-10-01	119244
2006-01-01	120732
2006-04-01	136332
2006-07-01	146132
2006-10-01	153828
2007-01-01	167533
2007-04-01	188145
2007-07-01	194708
2007-10-01	190163
2008-01-01	233336
2008-04-01	296113
2008-07-01	245557
2008-10-01	278324
2009-01-01	285546
2009-04-01	328083
2009-07-01	367279
2009-10-01	378182
2010-01-01	374119
2010-04-01	350591
2010-07-01	414311
2010-10-01	443070
2011-01-01	442689
2011-04-01	473519
2011-07-01	448538
2011-10-01	468655
2012-01-01	513859
2012-04-01	500242
2012-07-01	533782
2012-10-01	513351
2013-01-01	505881
2013-04-01	460051
2013-07-01	468882
2013-10-01	469940
2014-01-01	489366
2014-04-01	521158
2014-07-01	511114
2014-10-01	508807
2015-01-01	488604
2015-04-01	495932
2015-07-01	461527
2015-10-01	492431
2016-01-01	521287
2016-04-01	514840
2016-07-01	530094
2016-10-01	494057
2017-01-01	531555
2017-04-01	513735
2017-07-01	517704
2017-10-01	540595
2018-01-01	542023