Bi-annual US dollars 1987-06-30 35 1987-12-31 42 1988-06-30 15 1988-12-31 31 1989-06-30 45 1989-12-31 56 1990-06-30 56 1990-12-31 71 1991-06-30 99 1991-12-31 105 1992-06-30 143 1992-12-31 89 1993-06-30 197 1993-12-31 182 1994-06-30 256 1994-12-31 274 1995-06-30 267 1995-12-31 352 1996-06-30 329 1996-12-31 541 1997-06-30 582 1997-12-31 658 1998-06-30 467 1998-12-31 421 1999-06-30 437