Bi-annual US dollars 1987-06-30 6 1987-12-31 8 1988-06-30 10 1988-12-31 9 1989-06-30 19 1989-12-31 15 1990-06-30 7 1990-12-31 6 1991-06-30 6 1991-12-31 7 1992-06-30 27 1992-12-31 36 1993-06-30 23 1993-12-31 56 1994-06-30 57 1994-12-31 53 1995-06-30 72 1995-12-31 60 1996-06-30 68 1996-12-31 96 1997-06-30 78 1997-12-31 114 1998-06-30 182 1998-12-31 223 1999-06-30 259