GJ is a 79-year-old woman with hypertension, diabetes, osteoporosis, depression, and New York Heart Association class II heart failure with a left ventricular ejection fraction of 30%. She is a potential candidate for an implantable cardioverter-defibrillator (ICD), and you would like to discuss this with her using evidence from a clinical trial. Which of the following statistics would be most helpful in explaining the possible survival benefit of an ICD?