Bi-annual US dollars 1987-06-30 56 1987-12-31 53 1988-06-30 36 1988-12-31 16 1989-06-30 9 1989-12-31 13 1990-06-30 26 1990-12-31 41 1991-06-30 31 1991-12-31 7 1992-06-30 10 1992-12-31 11 1993-06-30 21 1993-12-31 22 1994-06-30 8 1994-12-31 14 1995-06-30 11 1995-12-31 31 1996-06-30 39 1996-12-31 21 1997-06-30 17 1997-12-31 7 1998-06-30 15 1998-12-31 8 1999-06-30 19