Bi-annual	US dollars
1987-06-30	18795
1987-12-31	19085
1988-06-30	20556
1988-12-31	23414
1989-06-30	20114
1989-12-31	24642
1990-06-30	21226
1990-12-31	23359
1991-06-30	24478
1991-12-31	28630
1992-06-30	29487
1992-12-31	22751
1993-06-30	25668
1993-12-31	26648
1994-06-30	31376
1994-12-31	33522
1995-06-30	20717
1995-12-31	21378
1996-06-30	22602
1996-12-31	25039
1997-06-30	24074
1997-12-31	23622
1998-06-30	25110
1998-12-31	28799
1999-06-30	27134