Bi-annual US dollars 1987-06-30 21 1987-12-31 23 1988-06-30 31 1988-12-31 36 1989-06-30 16 1989-12-31 18 1990-06-30 3 1990-12-31 12 1991-06-30 11 1991-12-31 37 1992-06-30 23 1992-12-31 17 1993-06-30 54 1993-12-31 49 1994-06-30 57 1994-12-31 136 1995-06-30 126 1995-12-31 226 1996-06-30 440 1996-12-31 757 1997-06-30 917 1997-12-31 1147 1998-06-30 837 1998-12-31 1468 1999-06-30 1053