Bi-annual	US dollars
1987-06-30	1187
1987-12-31	1147
1988-06-30	1175
1988-12-31	960
1989-06-30	922
1989-12-31	1035
1990-06-30	1034
1990-12-31	1102
1991-06-30	1268
1991-12-31	1373
1992-06-30	1444
1992-12-31	1567
1993-06-30	2143
1993-12-31	2204
1994-06-30	2571
1994-12-31	3232
1995-06-30	3159
1995-12-31	2892
1996-06-30	2776
1996-12-31	2950
1997-06-30	3590
1997-12-31	4887
1998-06-30	5354
1998-12-31	5200
1999-06-30	4313