Bi-annual US dollars 1987-06-30 435 1987-12-31 536 1988-06-30 498 1988-12-31 510 1989-06-30 414 1989-12-31 414 1990-06-30 296 1990-12-31 426 1991-06-30 342 1991-12-31 355 1992-06-30 350 1992-12-31 270 1993-06-30 345 1993-12-31 387 1994-06-30 458 1994-12-31 426 1995-06-30 375 1995-12-31 575 1996-06-30 525 1996-12-31 668 1997-06-30 654 1997-12-31 614 1998-06-30 667 1998-12-31 729 1999-06-30 686