Measure based on data from another measure with condition

Indeed I need calculate mix factor, 

I've got a lot of items, some of them were produced in this year, but weren't in previous? and some of them weren' produce this year, but were in previous period. And I need to calculate (Value per position this year - Value per position previos year) in case if or Value per position this year =0 or Value per position previous year =0. This is full task