Bi-annual	US dollars
1987-06-30	21374
1987-12-31	21936
1988-06-30	20920
1988-12-31	20756
1989-06-30	20167
1989-12-31	17260
1990-06-30	13490
1990-12-31	10828
1991-06-30	10935
1991-12-31	9879
1992-06-30	11323
1992-12-31	11287
1993-06-30	9437
1993-12-31	9987
1994-06-30	8693
1994-12-31	9329
1995-06-30	9850
1995-12-31	9367
1996-06-30	8903
1996-12-31	9791
1997-06-30	11464
1997-12-31	19556
1998-06-30	21798
1998-12-31	21715
1999-06-30	19970