Bi-annual	US dollars
1987-06-30	1840
1987-12-31	1678
1988-06-30	1448
1988-12-31	1184
1989-06-30	1129
1989-12-31	1034
1990-06-30	1116
1990-12-31	1233
1991-06-30	1406
1991-12-31	1634
1992-06-30	1671
1992-12-31	1504
1993-06-30	1870
1993-12-31	1825
1994-06-30	2133
1994-12-31	2524
1995-06-30	2968
1995-12-31	3861
1996-06-30	4139
1996-12-31	5295
1997-06-30	5934
1997-12-31	6918
1998-06-30	5630
1998-12-31	5531
1999-06-30	4683