The mortality measured in China is about 2%. Outside of China, I read it was rather 0.15%. And what I read is the 2% is based on the number of people who show up at the hospital with symptoms and get diagnosed. The doctors think there is a large but unknown population out there, with milder symptoms, who don't show up. Understandly. If you have what looks like a cold, you don't really want to go to the place where everyone is contaminated with the coronavirus.

So it looks like 2% is kind of the upper bound but that the actual rate will be lower.

This is wrong. The only way to get 0.15 is by dividing dead over total cases - which is not the correct math since most people infected are still ongoing.

You have to divide dead over dead+recovered, and outside of China those numbers are still too small to get a reliable number.

In China it is 2% outside Wuhan, but inside Wuhan it is over 4% since the medical system has broken down.