Index and Matching Data Results

[derivative_x]

I'm having some trouble figuring how to write a formula that will take my monthly results and copy that month into the yearly total whenever I put C (c for current) under the monthly total. I figure that I would have to match and index the results, but I'm not sure how.

When the year is up though, I simply just sum up the results copy and paste and move on to the next year.

Any ideas?

[Søren Larsen]

I can't see exactly from your attachment how you want this done. Is it the yellow shaded area you want a formula for? should the results be 5, 7 and 16 for D4, D5 and D6 respectively?