Bi-annual	US dollars
1987-06-30	7505
1987-12-31	8835
1988-06-30	8688
1988-12-31	8969
1989-06-30	9368
1989-12-31	11466
1990-06-30	11326
1990-12-31	11818
1991-06-30	9834
1991-12-31	10934
1992-06-30	10480
1992-12-31	12338
1993-06-30	16048
1993-12-31	19932
1994-06-30	17872
1994-12-31	20939
1995-06-30	21228
1995-12-31	18854
1996-06-30	21463
1996-12-31	20520
1997-06-30	20753
1997-12-31	22320
1998-06-30	24799
1998-12-31	25744
1999-06-30	28345