Bi-annual US dollars 1987-06-30 16 1987-12-31 9 1988-06-30 14 1988-12-31 4 1989-06-30 12 1989-12-31 2 1990-06-30 12 1990-12-31 12 1991-06-30 26 1991-12-31 30 1992-06-30 59 1992-12-31 121 1993-06-30 120 1993-12-31 80 1994-06-30 15 1994-12-31 13 1995-06-30 6 1995-12-31 3 1996-06-30 37 1996-12-31 68 1997-06-30 62 1997-12-31 38 1998-06-30 33 1998-12-31 23 1999-06-30 20