Bi-annual US dollars 1987-06-30 108 1987-12-31 100 1988-06-30 128 1988-12-31 199 1989-06-30 102 1989-12-31 174 1990-06-30 188 1990-12-31 272 1991-06-30 206 1991-12-31 385 1992-06-30 299 1992-12-31 342 1993-06-30 420 1993-12-31 260 1994-06-30 289 1994-12-31 441 1995-06-30 367 1995-12-31 262 1996-06-30 382 1996-12-31 609 1997-06-30 770 1997-12-31 788 1998-06-30 1310 1998-12-31 1481 1999-06-30 861