If we have a $3\times 3$ matrix of information where the row totals describe the total goods produced by a particular company and the column totals provide the total for a particular type of good for all companies how would I create a weighted average that tells me the average percentage Good A takes up, out of all production, for all companies? Is it necessary to weigh by company if the total number of products produced is, say, $10,50$, and $20$?