According to a recent CDC report, in 2009–2010:

• 81% of emergency department (ED) patients were discharged for follow-up care as needed
• 16% of ED visits ended with the patient being admitted to the hospital
• 2% of ED visits ended with the patient leaving without completing the visit
• Less than 1% ended in the patient’s death

Source: "One in five Americans report visiting emergency room at least once in the past year," Centers for Disease Control and Prevention Press Release, May 30, 2013, http://www.cdc.gov/media/releases/2013/p0530-emergency-room.html