Bi-annual US dollars 1987-06-30 363 1987-12-31 443 1988-06-30 452 1988-12-31 517 1989-06-30 468 1989-12-31 501 1990-06-30 504 1990-12-31 513 1991-06-30 435 1991-12-31 454 1992-06-30 426 1992-12-31 314 1993-06-30 287 1993-12-31 312 1994-06-30 326 1994-12-31 418 1995-06-30 409 1995-12-31 422 1996-06-30 332 1996-12-31 332 1997-06-30 356 1997-12-31 373 1998-06-30 492 1998-12-31 334 1999-06-30 334