Bi-annual US dollars 1987-06-30 94 1987-12-31 92 1988-06-30 84 1988-12-31 76 1989-06-30 60 1989-12-31 58 1990-06-30 47 1990-12-31 41 1991-06-30 32 1991-12-31 49 1992-06-30 34 1992-12-31 29 1993-06-30 41 1993-12-31 43 1994-06-30 54 1994-12-31 58 1995-06-30 60 1995-12-31 65 1996-06-30 70 1996-12-31 79 1997-06-30 75 1997-12-31 74 1998-06-30 70 1998-12-31 65 1999-06-30 60