Wheat:  Net sales of 273,000 metric tons for delivery in the 2018/2019 were down 61 percent from the previous week and 37 percent from the prior 4-week average.   Corn:  Net sales of 548,000 MT for 2018/2019 were up 2 percent from the previous week, but down 18 percent from the prior 4-week average.   Soybeans:  Net sales of 270,400 MT for 2018/2019 were down 86 percent from the previous week and 76 percent from the prior 4-week average.  Soybean Cake and Meal:  Net sales of 152,100 MT for 2018/2019 were down 20 percent from the previous week, but up 2 percent from the prior 4-week average.  Soybean Oil:  Net sales of 33,800 MT for 2018/2019 were down 8 percent from the previous wee...