Bi-annual US dollars 1987-06-30 4254 1987-12-31 3931 1988-06-30 4051 1988-12-31 4184 1989-06-30 3446 1989-12-31 3344 1990-06-30 1843 1990-12-31 693 1991-06-30 1717 1991-12-31 648 1992-06-30 540 1992-12-31 597 1993-06-30 720 1993-12-31 959 1994-06-30 798 1994-12-31 634 1995-06-30 616 1995-12-31 625 1996-06-30 601 1996-12-31 621 1997-06-30 626 1997-12-31 800 1998-06-30 820 1998-12-31 869 1999-06-30 856