Mortality is taken over the population as a whole. You want the case fatality rate (probability of death if you're infected), which in the US is 7-9%. Globally, some countries have TB case rates >30%.

TB is a very ancient, very scary disease that's co-evolved with us. It's not much of an exaggeration to say that large parts of modern medicine were invented specifically to get a handle on TB because it has historically ravaged entire populations when left untreated.