Bi-annual US dollars 1987-06-30 2675 1987-12-31 2008 1988-06-30 2204 1988-12-31 2072 1989-06-30 2561 1989-12-31 2219 1990-06-30 3601 1990-12-31 4089 1991-06-30 3879 1991-12-31 4102 1992-06-30 3949 1992-12-31 2677 1993-06-30 2659 1993-12-31 2737 1994-06-30 2400 1994-12-31 2984 1995-06-30 3037 1995-12-31 2874 1996-06-30 3205 1996-12-31 4057 1997-06-30 3991 1997-12-31 4436 1998-06-30 6871 1998-12-31 6849 1999-06-30 8899