Bi-annual US dollars 1987-06-30 2 1987-12-31 6 1988-06-30 22 1988-12-31 4 1989-06-30 0 1989-12-31 0 1990-06-30 0 1990-12-31 2 1991-06-30 2 1991-12-31 0 1992-06-30 49 1992-12-31 44 1993-06-30 42 1993-12-31 46 1994-06-30 43 1994-12-31 22 1995-06-30 25 1995-12-31 39 1996-06-30 42 1996-12-31 24 1997-06-30 30 1997-12-31 31 1998-06-30 30 1998-12-31 17 1999-06-30 22