Bi-annual US dollars 1987-06-30 16 1987-12-31 0 1988-06-30 188 1988-12-31 231 1989-06-30 0 1989-12-31 198 1990-06-30 218 1990-12-31 164 1991-06-30 222 1991-12-31 293 1992-06-30 257 1992-12-31 159 1993-06-30 83 1993-12-31 0 1994-06-30 35 1994-12-31 142 1995-06-30 200 1995-12-31 242 1996-06-30 188 1996-12-31 53 1997-06-30 0 1997-12-31 0 1998-06-30 0 1998-12-31 5 1999-06-30 11