Bi-annual US dollars 1987-06-30 168 1987-12-31 185 1988-06-30 196 1988-12-31 134 1989-06-30 144 1989-12-31 184 1990-06-30 215 1990-12-31 226 1991-06-30 170 1991-12-31 189 1992-06-30 204 1992-12-31 162 1993-06-30 341 1993-12-31 186 1994-06-30 265 1994-12-31 488 1995-06-30 286 1995-12-31 309 1996-06-30 435 1996-12-31 320 1997-06-30 589 1997-12-31 619 1998-06-30 842 1998-12-31 682 1999-06-30 659