One study [1] gives these annual numbers: 56,000 emergency room visits, 26,000 hospitalizations, and 458 fatalities. They further estimate about 75% of the fatalities are intentional overdoses, and 25% unintentional. Though I recall reading elsewhere that the majority of the non-fatal cases are accidental overdoses, e.g. from unwittingly taking multiple products that have acetaminophen as a component.