The problem with how Salling does it, is it's only based on ownership of the product. Someone could for example produce and manufacture 100% of the product in USA and then ship it to Denmark, but if the owner is european, then it'll be marked as a european product.
Usually country where it was made. Food and drink that is sold in europe is usually made in europe (at least the processed kinds, raw ingredients are often from elsewhere), but if the brand/brand owner is american, most of the actual profits go to the US.