Bi-annual	US dollars
1987-06-30	15807
1987-12-31	14564
1988-06-30	13595
1988-12-31	11770
1989-06-30	12995
1989-12-31	11960
1990-06-30	11026
1990-12-31	10195
1991-06-30	9847
1991-12-31	10454
1992-06-30	11753
1992-12-31	11063
1993-06-30	15506
1993-12-31	16951
1994-06-30	16639
1994-12-31	18497
1995-06-30	19249
1995-12-31	22516
1996-06-30	22352
1996-12-31	24762
1997-06-30	28572
1997-12-31	29267
1998-06-30	28563
1998-12-31	28127
1999-06-30	25579