Bi-annual US dollars 1987-06-30 993 1987-12-31 1000 1988-06-30 1141 1988-12-31 1195 1989-06-30 1378 1989-12-31 1446 1990-06-30 1404 1990-12-31 1106 1991-06-30 1039 1991-12-31 1339 1992-06-30 1462 1992-12-31 1667 1993-06-30 1601 1993-12-31 797 1994-06-30 753 1994-12-31 393 1995-06-30 310 1995-12-31 309 1996-06-30 253 1996-12-31 171 1997-06-30 273 1997-12-31 169 1998-06-30 318 1998-12-31 251 1999-06-30 296