Bi-annual US dollars 1987-06-30 0 1987-12-31 0 1988-06-30 0 1988-12-31 0 1989-06-30 0 1989-12-31 0 1990-06-30 0 1990-12-31 0 1991-06-30 0 1991-12-31 0 1992-06-30 0 1992-12-31 0 1993-06-30 0 1993-12-31 139 1994-06-30 49 1994-12-31 113 1995-06-30 143 1995-12-31 132 1996-06-30 155 1996-12-31 235 1997-06-30 368 1997-12-31 265 1998-06-30 510 1998-12-31 210 1999-06-30 254