The Settlers III/Goods

Supply and demand

 * 3 bakeries requires 1 mill.
 * 3 pig farms requires 1 slaughter house.
 * 1 bakery or pig farm requires 1 grain farm.
 * 1 waterworks for every 2 grain farms.
 * 2 mines requires 1 pig farm or bakery.
 * 100% iron mining + 200% coal mining requires 2 iron melters and 2 weapon smiths.