A unique situation has arisen for quite an accurate estimate of the CFR of COVID-19. Among individuals onboard the Diamond Princess cruise ship, data on the denominator are fairly robust. The outbreak of COVID-19 led passengers to be quarantined between Jan 20, and Feb 29, 2020. This scenario provided a population living in a defined territory without most other confounders, such as imported cases, defaulters of screening, or lack of testing capability. 3711 passengers and crew were onboard, of whom 705 became sick and tested positive for COVID-19 and 10 dead giving a CFR of 1.42%. Lets say everyone got sick. . . then the CFR would still be 0.34%.
*Note 15 patients are still in critical condition.

If the passengers onboard were generally of an older age, the CFR in a healthy, younger population could be lower, but it appears that it was in general a healthier but slightly older population.