Somewhere around 0.5% IMO (with good medical support). Iceland has tested 5%+ of their population, and currently, it is 0.46% there, with 8 cases in serious/critical condition (8 deaths so far, so if all those in serious conditions die, then the death rate increases to 0.9%). Diamond Princess with 100% testing has a death rate of 1.7% (which can still go higher, some people are still in bad conditions), but they had a very skewed distribution (it is a cruise ship after all, so old people were over-represented and young people under-representing).
I think it might be slightly lower than 0.5%, and I would be extremely surprised if it is over 1%.