That's the upper bound on the fatality rate if it infected the whole population. In actuality not even Hubei had 0.1% of the population infected, so the numbers

That's the upper bound on the fatality rate if it infected the whole population. In actuality not even Hubei had 0.1% of the population infected, so the numbers will be higher if it mostly infects older people (Italy), and lower if it mostly infects younger people (South Korea).