Bi-annual US dollars 1987-06-30 21 1987-12-31 94 1988-06-30 96 1988-12-31 116 1989-06-30 98 1989-12-31 103 1990-06-30 140 1990-12-31 104 1991-06-30 97 1991-12-31 97 1992-06-30 82 1992-12-31 82 1993-06-30 90 1993-12-31 106 1994-06-30 120 1994-12-31 156 1995-06-30 111 1995-12-31 129 1996-06-30 148 1996-12-31 187 1997-06-30 251 1997-12-31 220 1998-06-30 175 1998-12-31 238 1999-06-30 136