I agree with Royster, it really depends on your store and market. There is no industry standard for my store. IF the industry is considered a franchise delivery/carry-out, then it applies only to those franchises. The ‘general’ standard for restaurant business is 30% (food costs, not paper, not chemicals, etc…).
I find it useful to look at total COGS vs food costs only. My total annual COGS is usually about 20%. But that # is unique to my business and location. As Piper mentioned in another thread, rents and operating costs also vary depending on location.
From what I see in the restaurant business, food cost ‘percentages’ in a ‘mature’ business, usually reflect pricing ability. The more pricing ability, the less discounts you require to maintain sales levels. In extremely competitive markets, you will have very little pricing ability and normally will have a higher food cost relative to sales price.