What percentage of people with COVID-19 are asymptomatic?

An overview of a few definitions before answering this question:

The word asymptomatic means a person does not have any signs or symptoms or infection. Estimates vary, but up to 50% of people infected with COVID-19 are asymptomatic. The word pre-symptomatic infected person means a person has the infection but has not yet developed symptoms but eventually develops symptoms. Symptomatic infected person means a person has the infection and the associated symptoms (e.g. fever, cough, shortness of breath).

The degree to which an asymptomatic infected person contributes to transmission of disease is also not known but evidence suggests that disease transmission occurs primarily by symptomatic infected persons to others who they are in close contact with through droplets or contaminated surfaces. Transmission is probably highest in the first ~3 days from the onset of symptoms.