The stats from NYC Department of Health as of this morning, regarding pre-existing conditions and age of deaths

This means that of deaths in NYC, the center of the outbreak, 1.7 percent had no pre-existing conditions. NYC Health says "Underlying illnesses include Diabetes, Lung Disease, Cancer, Immunodeficiency, Heart Disease, Hypertension, Asthma, Kidney Disease, and GI/Liver Disease."

Note that there are still cases pending, so those numbers are not final, of course.