Bi-annual	US dollars
1987-06-30	1079
1987-12-31	1361
1988-06-30	1187
1988-12-31	749
1989-06-30	1507
1989-12-31	1395
1990-06-30	2170
1990-12-31	1366
1991-06-30	1155
1991-12-31	1257
1992-06-30	1490
1992-12-31	1959
1993-06-30	1654
1993-12-31	2566
1994-06-30	3188
1994-12-31	3501
1995-06-30	4446
1995-12-31	3468
1996-06-30	3755
1996-12-31	3474
1997-06-30	5072
1997-12-31	4026
1998-06-30	3903
1998-12-31	3468
1999-06-30	3485