I am trying to keep a running total of weights of material, sorted by
material type on a seperate worksheet (reports worksheet). I have created a
table of material types and would like to keep a running monthly total for
each material type. Each Here is my example.

In a worksheet (revenue) my material type is listed as below
C6:C1129 =gravel
=grain
=soil
I have 20 different types of material with corresponding weights listed in
I6:I1129 in the same worksheet.

I then have material types listed in rows in a summary table in a seperate
worksheet (reports), with the months of the year in columns.
Any suggestions would be greatly appreciated.