Bi-annual US dollars 1987-06-30 82 1987-12-31 66 1988-06-30 128 1988-12-31 87 1989-06-30 160 1989-12-31 156 1990-06-30 153 1990-12-31 274 1991-06-30 201 1991-12-31 211 1992-06-30 154 1992-12-31 79 1993-06-30 114 1993-12-31 225 1994-06-30 191 1994-12-31 227 1995-06-30 153 1995-12-31 219 1996-06-30 158 1996-12-31 166 1997-06-30 279 1997-12-31 441 1998-06-30 494 1998-12-31 451 1999-06-30 555