Half of This Can Is 90% Lentil

Seen on a can of soup at the corner grocery: "70% Organic." Does this even mean anything? Is that by weight or by volume? Are they including water in that calculation?

By my calculation, that soup could plausibly be up to 30% Twinkie-fed genetically modified beef.

I'm actually curious whether this is a widespread thing or not, and whether kind-of-organic food could cut out a swath of market share from actually-organic food.