Bi-annual US dollars 1987-06-30 61 1987-12-31 8 1988-06-30 17 1988-12-31 22 1989-06-30 31 1989-12-31 5 1990-06-30 10 1990-12-31 2 1991-06-30 2 1991-12-31 2 1992-06-30 4 1992-12-31 29 1993-06-30 54 1993-12-31 93 1994-06-30 8 1994-12-31 0 1995-06-30 5 1995-12-31 62 1996-06-30 135 1996-12-31 19 1997-06-30 28 1997-12-31 25 1998-06-30 25 1998-12-31 15 1999-06-30 11