Finding Average

Not sure if am being thick today but I am trying to work out the Average between a number of different rows, I know if was adding I would use the SUMIF formula

I have attached what am trying to do.
when you look at the contractID of BIRM I want to find the Average of all questions related to each questionID so I want to know average of all contracts for BIRM for QuestionID 1 and so on.

BIRM contracts go from row18 to 66

I then want to do the same for LDS contracts row74 to 201

then finally I want to find the average of BIRM & LDS for each questionID

How can I exclude any Zero too?