Bi-annual US dollars 1987-06-30 331 1987-12-31 379 1988-06-30 409 1988-12-31 333 1989-06-30 414 1989-12-31 274 1990-06-30 262 1990-12-31 295 1991-06-30 284 1991-12-31 390 1992-06-30 499 1992-12-31 426 1993-06-30 737 1993-12-31 610 1994-06-30 568 1994-12-31 688 1995-06-30 380 1995-12-31 564 1996-06-30 1175 1996-12-31 901 1997-06-30 1226 1997-12-31 2835 1998-06-30 3388 1998-12-31 4470 1999-06-30 5937