单位：美元/吨 

      时间       美湾     阿根廷
     6/16/05    52.05      53.55
     6/15/05    52.76      54.26
     6/14/05    53.34      54.84 
     6/13/05    53.34      54.84
     6/10/05    58.11      56.61
      6/9/05    55.93      57.43
      6/8/05    56.26      57.76
      6/7/05    56.57      58.07   
      6/6/05    56.57      58.07
      6/3/05    56.32      57.82
      6/2/05    56.21      57.71
      6/1/05    56.21      57.71
     5/30/05    56.14      57.64
     5/27/05    56.47      57.97
     5/26/05    56.58 &n