Bi-annual US dollars 1987-06-30 537 1987-12-31 506 1988-06-30 406 1988-12-31 622 1989-06-30 592 1989-12-31 613 1990-06-30 562 1990-12-31 621 1991-06-30 514 1991-12-31 622 1992-06-30 611 1992-12-31 565 1993-06-30 500 1993-12-31 492 1994-06-30 352 1994-12-31 410 1995-06-30 398 1995-12-31 434 1996-06-30 236 1996-12-31 419 1997-06-30 359 1997-12-31 489 1998-06-30 479 1998-12-31 491 1999-06-30 481