Bi-annual US dollars 1987-06-30 15 1987-12-31 15 1988-06-30 15 1988-12-31 9 1989-06-30 14 1989-12-31 32 1990-06-30 115 1990-12-31 8 1991-06-30 18 1991-12-31 21 1992-06-30 49 1992-12-31 38 1993-06-30 42 1993-12-31 16 1994-06-30 77 1994-12-31 9 1995-06-30 116 1995-12-31 43 1996-06-30 20 1996-12-31 33 1997-06-30 48 1997-12-31 87 1998-06-30 135 1998-12-31 151 1999-06-30 88