Quarter	US dollars
1999-03-31	22231
1999-06-30	20310
1999-09-30	19672
1999-12-31	20163
2000-03-31	20863
2000-06-30	18482
2000-09-30	18106
2000-12-31	17591
2001-03-31	16534
2001-06-30	16207
2001-09-30	15452
2001-12-31	16920
2002-03-31	17420
2002-06-30	17379
2002-09-30	16222
2002-12-31	17884
2003-03-31	15876
2003-06-30	15539
2003-09-30	17083
2003-12-31	15494
2004-03-31	20329
2004-06-30	16609
2004-09-30	15285
2004-12-31	16666
2005-03-31	14933
2005-06-30	15367
2005-09-30	18274
2005-12-31	17803
2006-03-31	21782
2006-06-30	23470
2006-09-30	27660
2006-12-31	23531
2007-03-31	23063
2007-06-30	26912
2007-09-30	25702
2007-12-31	24983
2008-03-31	25366
2008-06-30	28001
2008-09-30	23925
2008-12-31	18615
2009-03-31	19032
2009-06-30	20325
2009-09-30	22667
2009-12-31	23280
2010-03-31	24024
2010-06-30	23402
2010-09-30	27181
2010-12-31	27208
2011-03-31	28665
2011-06-30	32553
2011-09-30	30760
2011-12-31	33483
2012-03-31	40698
2012-06-30	34127
2012-09-30	33177
2012-12-31	35843
2013-03-31	34895
2013-06-30	28870
2013-09-30	38452
2013-12-31	40527
2014-03-31	33180
2014-06-30	32133
2014-09-30	32054
2014-12-31	31419
2015-03-31	33020
2015-06-30	31471
2015-09-30	30215
2015-12-31	32234
2016-03-31	18905
2016-06-30	18382
2016-09-30	17585
2016-12-31	16794
2017-03-31	17297
2017-06-30	15668
2017-09-30	17424
2017-12-31	16315
2018-03-31	17158
2018-06-30	15700
2018-09-30	16013
2018-12-31	17572
2019-03-31	17521
2019-06-30	19511
2019-09-30	18067
2019-12-31	16198
2020-03-31	14428
2020-06-30	14188
2020-09-30	13029
2020-12-31	20401
2021-03-31	16913
2021-06-30	17299
2021-09-30	16037
2021-12-31	17135
2022-03-31	19640
2022-06-30	19146
2022-09-30	19394
2022-12-31	23325
2023-03-31	25641
2023-06-30	29119
2023-09-30	27508