8% ?
I found this little tidbit at mounteverest.net:
Today, Everest has hosted close to 2,000 successful summits. 179 people have perished giving a fatality rate of 9.3% (fatality rate is defined as successful summits compared to fatalities). However, since 1990 there has been an explosion of summiteers and fatality statistics have changed. Up to 1990 the Everest fatality rate is a whopping 37%, yet from 1990 until today the rate has dropped to 4.4%.