I have a table that looks like the example below.

There are several of these tanks with input data on each sheet and there are
12 sheets in the workbook. I want to make a page where I calculate the
average of all the input data, irrespective of which tank the data comes
from. So the average of all the input data. How do I do this?

Tank A.
Date 10 12 13 17 20
Result 2 3 3 4 3



Average 2 3 3 4 3
Bulknr. 106445 106457 106457 106502
Sats. AA AA AA AA
Sign HE HE HE LF

Tank B.
Date 10 12 13 17 20
Result 2 3 3 4 3



Average 2 3 3 4 3
Bulknr. 106445 106457 106457 106502
Sats. AA AA AA AA
Sign HE HE HE LF