Bi-annual US dollars 1987-06-30 0 1987-12-31 0 1988-06-30 0 1988-12-31 0 1989-06-30 0 1989-12-31 0 1990-06-30 0 1990-12-31 0 1991-06-30 0 1991-12-31 0 1992-06-30 0 1992-12-31 0 1993-06-30 0 1993-12-31 12 1994-06-30 42 1994-12-31 8 1995-06-30 6 1995-12-31 11 1996-06-30 44 1996-12-31 158 1997-06-30 77 1997-12-31 194 1998-06-30 155 1998-12-31 55 1999-06-30 44