Bi-annual US dollars 1987-06-30 10 1987-12-31 13 1988-06-30 10 1988-12-31 7 1989-06-30 6 1989-12-31 15 1990-06-30 3 1990-12-31 8 1991-06-30 6 1991-12-31 9 1992-06-30 4 1992-12-31 20 1993-06-30 18 1993-12-31 16 1994-06-30 22 1994-12-31 56 1995-06-30 51 1995-12-31 55 1996-06-30 20 1996-12-31 22 1997-06-30 27 1997-12-31 214 1998-06-30 125 1998-12-31 188 1999-06-30 148