Calculation of yearly growth for several areas

I love the "if then else" function - maybe to much.
My problem is that I would like to calculate growth from one year to the next for, let say, 7 years in a row for different areas. 

To to this I create a dummy variable (accumulated count members). I use this dummy to define in wich row I want growth from 2011 to 2012 to appear. It used to work just fine, but now for the case in question, the formular seems to be to long and I can only get 3 years growth. I imagine there must be a better way to do this. 

Can anyone help me?

Eg. Current formular: if sum(c2, 0, m1) = 2 then (sum(0, d-5, m1) - sum(0, d-6, m1)) / sum(d-7, d-6, m1) else if….. (continues *9)