Excel formula help

I need a weighted abstract score calculated. I have the weighted sum already calculated. Here is the formula: Weighted Sum of Scores- this is calculated per abstract- take each reviewer's score for that abstract and divide it by the "weight"(weight score provided) for that reviewer. The problem is that I have 600+ columns that need to be included in the calculation, some of which have no number in them, so they need to be ignored. See sheet provided.