Quarter	Millions of US Dollars
1973-04-01	10
1973-07-01	9
1973-10-01	9
1974-01-01	8
1974-04-01	8
1974-07-01	8
1974-10-01	9
1975-01-01	9
1975-04-01	10
1975-07-01	9
1975-10-01	9
1976-01-01	9
1976-04-01	8
1976-07-01	18
1976-10-01	19
1977-01-01	18
1977-04-01	19
1977-07-01	19
1977-10-01	19
1978-01-01	20
1978-04-01	20
1978-07-01	20
1978-10-01	21
1979-01-01	20
1979-04-01	20
1979-07-01	21
1979-10-01	21
1980-01-01	20
1980-04-01	21
1980-07-01	23
1980-10-01	22
1981-01-01	20
1981-04-01	18
1981-07-01	19
1981-10-01	20
1982-01-01	18
1982-04-01	17
1982-07-01	16
1982-10-01	17
1983-01-01	17
1983-04-01	16
1983-07-01	16
1983-10-01	15
1984-01-01	16
1984-04-01	15
1984-07-01	14
1984-10-01	13
1985-01-01	13
1985-04-01	13
1985-07-01	15
1985-10-01	15
1986-01-01	16
1986-04-01	17
1986-07-01	18
1986-10-01	19
1987-01-01	20
1987-04-01	16
1987-07-01	15
1987-10-01	18
1988-01-01	17
1988-04-01	16
1988-07-01	15
1988-10-01	16
1989-01-01	6
1989-04-01	6
1989-07-01	6
1989-10-01	7
1990-01-01	7
1998-01-01	1277
1998-04-01	1277
1998-07-01	1272
1998-10-01	1272
1999-01-01	1267
1999-04-01	1267
1999-07-01	1261
1999-10-01	1261
2000-01-01	1256
2000-04-01	1256
2000-07-01	1251
2000-10-01	1251
2001-01-01	1245
2001-04-01	1245
2001-07-01	1240
2001-10-01	1240
2002-01-01	1235
2002-04-01	1235
2002-07-01	1229
2002-10-01	1229
2003-01-01	1224
2003-04-01	1224
2003-07-01	1218
2003-10-01	1218
2004-01-01	1211
2004-04-01	1211
2004-07-01	1205
2004-10-01	1205
2005-01-01	1199
2005-04-01	1199
2005-07-01	1192
2005-10-01	1192
2006-01-01	1186
2006-04-01	1186
2006-07-01	1179
2006-10-01	1179
2007-01-01	1173
2007-04-01	1173
2007-07-01	1167
2007-10-01	1167
2008-01-01	1158
2008-04-01	1158
2008-07-01	1150
2008-10-01	1150
2009-01-01	1141
2009-04-01	1141
2009-07-01	1133
2009-10-01	1133
2010-01-01	1124
2010-04-01	2605
2010-07-01	2592
2010-10-01	2592
2011-01-01	2580
2011-04-01	2580
2011-07-01	2567
2011-10-01	2567
2012-01-01	2554
2012-04-01	2554
2012-07-01	2537
2012-10-01	2537
2013-01-01	2520
2013-04-01	2520
2013-07-01	2503
2013-10-01	2503
2014-01-01	2486
2014-04-01	2486
2014-07-01	3219
2014-10-01	3219
2015-01-01	4202
2015-04-01	4202
2015-07-01	4185
2015-10-01	4434
2016-01-01	4428
2016-04-01	4422
2016-07-01	4402
2016-10-01	4388
2017-01-01	4370
2017-04-01	6349
2017-07-01	6362
2017-10-01	6378
2018-01-01	8479
2018-04-01	8309