But as people learn more they are getting better ideas on the disease progression. Every number has many assumptions built into it.
Seems like very little is known about how many people have had it and were either asymptomatic or minimally symptomatic. So the actual mortality rate is highly debated, without much real info. Not enough testing kits anywhere (in particular the USA and China) is making this difficult. Even with testing it's hard because and unknown number of people can just shrug it off.
But if you do go to the hospital and they are completely overwhelmed, treating people in hallways, etc the death rate is 10%. There were times in Wuhan where this was true.
If somewhat overwhelmed, able to treat, but not put on a full ventilator, but able to do supportive care (anti-virals, fluids, oxygen, etc) looks like the mortality rate (again for those that go to the hospital) is under 5%. Wuhan has been like this for some days now.
For those that go to the hospital where they aren't overwhelmed and you can get full supportive care up to and including a full ventilator the mortality rate, again for those that go to a hospital, is under 1%. This is seen in numerous countries that have very few cases.