Bi-annual	US dollars
1987-06-30	6485
1987-12-31	6597
1988-06-30	6425
1988-12-31	6198
1989-06-30	6067
1989-12-31	5450
1990-06-30	4432
1990-12-31	4262
1991-06-30	4355
1991-12-31	4554
1992-06-30	4461
1992-12-31	4227
1993-06-30	4652
1993-12-31	4611
1994-06-30	4349
1994-12-31	4797
1995-06-30	4694
1995-12-31	4484
1996-06-30	4223
1996-12-31	4566
1997-06-30	4913
1997-12-31	5372
1998-06-30	5554
1998-12-31	4994
1999-06-30	4562