Sorry, bc, I thought Dave wanted a ratio (ie, straight answer.) I know that Joe suggested he talk to his contractor but in case he (Dave) is hesitant to do so (which would not be unreasonable since he (Joe) is 'asking' the forum and not his contractor), I thought I'd recommend another option. Yet, my other 'options' may send him back to, well ..., his contractor. I was assuming that Dave wanted to 'confirm' the ratio from another 'source' and it not be from his contractor.
I apologize to you/Joe if my additional posts implied that the question wasn't answered. Again, I was just 'adding' information whether it is used or not, I guess I'll never know.