Brown sugar is 70% white?

New Scientist Back Page - I'm sweet enough

At one time brown sugar was sugar that hadn't been fully refined, and if you buy coarse "raw" sugar this may still be the case. But today's brown sugar is most often made by adding molasses back into fine white sugar. Manufacturers do this because they can more easily control the proportions of sucrose and molasses and the size of the white sugar crystals, resulting in a more uniform product. You can do the same at home if you run out of brown sugar. Mix about nine parts caster sugar with one part molasses and stir, stir, stir. The fact that brown sugar is really 90 per cent white sugar means that they both have about the same energy content of 17 kilocalories per teaspoon. Certainly there are more minerals such as iron and calcium in molasses, but you'd need to swallow about a cup of the stuff to get close to your daily requirement, which would incidentally contain about 50 per cent of your daily energy needs.
A tablespoon of blackstrap molasses, which is still 70 per cent sugar, has an iron content which is similar to a steak and it also tastes great on special high-protein porridges.