Bi-annual	US dollars
1987-06-30	1226
1987-12-31	1294
1988-06-30	1283
1988-12-31	1036
1989-06-30	1040
1989-12-31	1134
1990-06-30	1310
1990-12-31	1329
1991-06-30	1448
1991-12-31	1545
1992-06-30	1549
1992-12-31	1620
1993-06-30	2018
1993-12-31	2406
1994-06-30	2753
1994-12-31	3310
1995-06-30	3839
1995-12-31	3137
1996-06-30	3395
1996-12-31	3830
1997-06-30	3996
1997-12-31	4335
1998-06-30	3268
1998-12-31	4187
1999-06-30	3007