Bi-annual US dollars 1987-06-30 152 1987-12-31 115 1988-06-30 220 1988-12-31 188 1989-06-30 181 1989-12-31 189 1990-06-30 227 1990-12-31 347 1991-06-30 182 1991-12-31 286 1992-06-30 658 1992-12-31 253 1993-06-30 896 1993-12-31 970 1994-06-30 949 1994-12-31 1128 1995-06-30 1087 1995-12-31 1464 1996-06-30 1955 1996-12-31 2357 1997-06-30 2886 1997-12-31 3514 1998-06-30 3905 1998-12-31 2852 1999-06-30 2711