Quarter	US dollars
1999-03-31	4616
1999-06-30	4803
1999-09-30	4684
1999-12-31	5066
2000-03-31	5306
2000-06-30	5296
2000-09-30	5439
2000-12-31	5984
2001-03-31	6175
2001-06-30	5714
2001-09-30	6015
2001-12-31	6167
2002-03-31	5742
2002-06-30	6862
2002-09-30	7505
2002-12-31	8613
2003-03-31	8336
2003-06-30	10808
2003-09-30	10382
2003-12-31	11454
2004-03-31	13023
2004-06-30	14333
2004-09-30	15094
2004-12-31	17389
2005-03-31	18877
2005-06-30	17189
2005-09-30	18663
2005-12-31	17996
2006-03-31	22411
2006-06-30	21956
2006-09-30	25157
2006-12-31	25109
2007-03-31	27962
2007-06-30	28570
2007-09-30	28107
2007-12-31	26247
2008-03-31	28774
2008-06-30	28430
2008-09-30	33752
2008-12-31	27043
2009-03-31	22298
2009-06-30	22511
2009-09-30	36247
2009-12-31	24083
2010-03-31	23052
2010-06-30	20576
2010-09-30	21633
2010-12-31	22267
2011-03-31	23951
2011-06-30	23263
2011-09-30	24242
2011-12-31	22370
2012-03-31	25078
2012-06-30	24854
2012-09-30	24363
2012-12-31	22363
2013-03-31	22453
2013-06-30	22582
2013-09-30	24836
2013-12-31	25263
2014-03-31	23689
2014-06-30	25354
2014-09-30	23417
2014-12-31	21766
2015-03-31	21392
2015-06-30	22456
2015-09-30	23898
2015-12-31	24124
2016-03-31	24273
2016-06-30	24941
2016-09-30	22965
2016-12-31	20372
2017-03-31	20184
2017-06-30	21009
2017-09-30	21581
2017-12-31	24013
2018-03-31	25074
2018-06-30	23794
2018-09-30	23458
2018-12-31	23271
2019-03-31	22464
2019-06-30	22208
2019-09-30	23060
2019-12-31	23726
2020-03-31	23669
2020-06-30	20983
2020-09-30	21485
2020-12-31	22931
2021-03-31	22004
2021-06-30	24138
2021-09-30	23741
2021-12-31	22142
2022-03-31	19545
2022-06-30	16659
2022-09-30	15485
2022-12-31	16886
2023-03-31	15373
2023-06-30	15388
2023-09-30	14389