Bi-annual US dollars 1987-06-30 18 1987-12-31 15 1988-06-30 14 1988-12-31 7 1989-06-30 11 1989-12-31 15 1990-06-30 14 1990-12-31 41 1991-06-30 36 1991-12-31 30 1992-06-30 38 1992-12-31 30 1993-06-30 101 1993-12-31 87 1994-06-30 171 1994-12-31 199 1995-06-30 218 1995-12-31 223 1996-06-30 238 1996-12-31 238 1997-06-30 158 1997-12-31 140 1998-06-30 45 1998-12-31 58 1999-06-30 54