Designing Great Beers suggests that not more than 10% of the fermentables come from sugar sources. And that 25-67 percent of the gravity of your beer should come from grain. So at first I'm just calculating a straight percentage on my own, then it occurs to me that it should be weighted differently for liquid vs dry extract, so I assume grains and sugars may have a different weight as well. So now I'm looking at the %/IBU column of the recipe design tab in BeerSmith, which I hadn't paid attention to before, thinking it was just had something to do with IBU's. But now I see that it is a dual purpose column, showing both the IBU percent for hops and the grain percentages. However, on inspection, it looks it's just a straight percentage, weighting grains, extract, and sugars all the same. Am I missing something? How do know what percentage of the gravity each ingredient is contributing???