Bi-annual US dollars 1987-06-30 90 1987-12-31 30 1988-06-30 60 1988-12-31 20 1989-06-30 91 1989-12-31 44 1990-06-30 63 1990-12-31 156 1991-06-30 167 1991-12-31 138 1992-06-30 103 1992-12-31 285 1993-06-30 383 1993-12-31 334 1994-06-30 511 1994-12-31 533 1995-06-30 803 1995-12-31 1017 1996-06-30 1552 1996-12-31 2092 1997-06-30 1822 1997-12-31 1423 1998-06-30 1644 1998-12-31 1594 1999-06-30 1898