Bi-annual US dollars 1987-06-30 19 1987-12-31 13 1988-06-30 14 1988-12-31 9 1989-06-30 6 1989-12-31 6 1990-06-30 5 1990-12-31 8 1991-06-30 6 1991-12-31 6 1992-06-30 2 1992-12-31 8 1993-06-30 3 1993-12-31 1 1994-06-30 5 1994-12-31 2 1995-06-30 3 1995-12-31 5 1996-06-30 9 1996-12-31 10 1997-06-30 13 1997-12-31 7 1998-06-30 18 1998-12-31 22 1999-06-30 14