Bi-annual US dollars 1987-06-30 10 1987-12-31 30 1988-06-30 7 1988-12-31 5 1989-06-30 9 1989-12-31 8 1990-06-30 10 1990-12-31 15 1991-06-30 13 1991-12-31 7 1992-06-30 6 1992-12-31 6 1993-06-30 12 1993-12-31 6 1994-06-30 9 1994-12-31 9 1995-06-30 10 1995-12-31 8 1996-06-30 11 1996-12-31 14 1997-06-30 12 1997-12-31 13 1998-06-30 18 1998-12-31 17 1999-06-30 14