Bi-annual US dollars 1987-06-30 2599 1987-12-31 3055 1988-06-30 2149 1988-12-31 2616 1989-06-30 2359 1989-12-31 3564 1990-06-30 3711 1990-12-31 3328 1991-06-30 2230 1991-12-31 2449 1992-06-30 2752 1992-12-31 2785 1993-06-30 3139 1993-12-31 3487 1994-06-30 3299 1994-12-31 3284 1995-06-30 2249 1995-12-31 2304 1996-06-30 2202 1996-12-31 2902 1997-06-30 3086 1997-12-31 4018 1998-06-30 3341 1998-12-31 2829 1999-06-30 3463