Week 1 Week 2 Week 3
Cym M. Share 5.46% 4.63% 0
Cym TRX 130 110
ADD TRX 2,381 2,377
TRX Needed 129 128
Difference 1 -18
Total Needed -17
Avg SOM

I want to calculate Avg SOM cell. I eter new data each week and want a
running average of Cym M. Share. I can't figure it out how to make it work.