Bi-annual US dollars 1987-06-30 23 1987-12-31 15 1988-06-30 20 1988-12-31 22 1989-06-30 17 1989-12-31 8 1990-06-30 16 1990-12-31 8 1991-06-30 0 1991-12-31 9 1992-06-30 11 1992-12-31 35 1993-06-30 11 1993-12-31 7 1994-06-30 5 1994-12-31 9 1995-06-30 0 1995-12-31 73 1996-06-30 89 1996-12-31 123 1997-06-30 166 1997-12-31 225 1998-06-30 310 1998-12-31 27 1999-06-30 233