Bi-annual US dollars 1987-06-30 461 1987-12-31 430 1988-06-30 377 1988-12-31 340 1989-06-30 229 1989-12-31 268 1990-06-30 272 1990-12-31 311 1991-06-30 306 1991-12-31 374 1992-06-30 419 1992-12-31 468 1993-06-30 477 1993-12-31 417 1994-06-30 543 1994-12-31 510 1995-06-30 542 1995-12-31 471 1996-06-30 441 1996-12-31 392 1997-06-30 376 1997-12-31 492 1998-06-30 507 1998-12-31 524 1999-06-30 763