Sorry BI but I think Simon is totally right and you totally wrong...however as Simon said it depend on first instance what you want to calculate...but according the general meaning of the words that you used your math is wrong. The correct lethal rate is according the infected population, which you can only estimate as there is not a real check. The one tested in hospital are only a fraction of the infected people. A lot of people are infected but have no symptoms.
What you estimate is only the death rate percentage of people who are in the hospital WITH covid... But is it an important number?
I don't think so...
IC