Bi-annual	US dollars
1987-06-30	4357
1987-12-31	4044
1988-06-30	3518
1988-12-31	3837
1989-06-30	3414
1989-12-31	2948
1990-06-30	2333
1990-12-31	2400
1991-06-30	2173
1991-12-31	2385
1992-06-30	2187
1992-12-31	1866
1993-06-30	2648
1993-12-31	2584
1994-06-30	2898
1994-12-31	3279
1995-06-30	3498
1995-12-31	3965
1996-06-30	4604
1996-12-31	6069
1997-06-30	6871
1997-12-31	7308
1998-06-30	7991
1998-12-31	7976
1999-06-30	6682