Bi-annual	US dollars
1987-06-30	6592
1987-12-31	6855
1988-06-30	6723
1988-12-31	6796
1989-06-30	6334
1989-12-31	6318
1990-06-30	5438
1990-12-31	4650
1991-06-30	4527
1991-12-31	4580
1992-06-30	4518
1992-12-31	4862
1993-06-30	4773
1993-12-31	3804
1994-06-30	3775
1994-12-31	3655
1995-06-30	3573
1995-12-31	3561
1996-06-30	2769
1996-12-31	3480
1997-06-30	4212
1997-12-31	3062
1998-06-30	3066
1998-12-31	3652
1999-06-30	4152