Quarter	US dollars
1999-03-31	6048
1999-06-30	6565
1999-09-30	6983
1999-12-31	7261
2000-03-31	6436
2000-06-30	6603
2000-09-30	6559
2000-12-31	6496
2001-03-31	6745
2001-06-30	7001
2001-09-30	7682
2001-12-31	7957
2002-03-31	6669
2002-06-30	6727
2002-09-30	6870
2002-12-31	6604
2003-03-31	6919
2003-06-30	7378
2003-09-30	7185
2003-12-31	6949
2004-03-31	8955
2004-06-30	9970
2004-09-30	9510
2004-12-31	9611
2005-03-31	10361
2005-06-30	9911
2005-09-30	11747
2005-12-31	12370
2006-03-31	12193
2006-06-30	14540
2006-09-30	15397
2006-12-31	15304
2007-03-31	16605
2007-06-30	16407
2007-09-30	21027
2007-12-31	17965
2008-03-31	20554
2008-06-30	19278
2008-09-30	17704
2008-12-31	15784
2009-03-31	14817
2009-06-30	14593
2009-09-30	19910
2009-12-31	18269
2010-03-31	14271
2010-06-30	13454
2010-09-30	14027
2010-12-31	13530
2011-03-31	13710
2011-06-30	14618
2011-09-30	15298
2011-12-31	12588
2012-03-31	14680
2012-06-30	14833
2012-09-30	14432
2012-12-31	15803
2013-03-31	17901
2013-06-30	15689
2013-09-30	15314
2013-12-31	15764
2014-03-31	14765
2014-06-30	14368
2014-09-30	14040
2014-12-31	13944
2015-03-31	13995
2015-06-30	15795
2015-09-30	15709
2015-12-31	15716
2016-03-31	16480
2016-06-30	18770
2016-09-30	19513
2016-12-31	18006
2017-03-31	17996
2017-06-30	16875
2017-09-30	17716
2017-12-31	18013
2018-03-31	18379
2018-06-30	17676
2018-09-30	15537
2018-12-31	15908
2019-03-31	15262
2019-06-30	15187
2019-09-30	16142
2019-12-31	16500
2020-03-31	17547
2020-06-30	18790
2020-09-30	16635
2020-12-31	16250
2021-03-31	17562
2021-06-30	17349
2021-09-30	18352
2021-12-31	17261
2022-03-31	15033
2022-06-30	14681
2022-09-30	14632
2022-12-31	13486
2023-03-31	12678
2023-06-30	13290
2023-09-30	14330