Bi-annual US dollars 1987-06-30 2 1987-12-31 4 1988-06-30 7 1988-12-31 7 1989-06-30 9 1989-12-31 10 1990-06-30 10 1990-12-31 12 1991-06-30 11 1991-12-31 17 1992-06-30 19 1992-12-31 21 1993-06-30 24 1993-12-31 24 1994-06-30 29 1994-12-31 41 1995-06-30 43 1995-12-31 48 1996-06-30 50 1996-12-31 51 1997-06-30 93 1997-12-31 58 1998-06-30 77 1998-12-31 50 1999-06-30 57