I found a much lower figure (4%!) for hellish experiences:
The Bruce Greyson Lecture from the International Association for Near-Death Studies 2004 Annual Conference
Peter Fenwick, M.D., F.R.C.Psych. Institute of Psychiatry, Kings College, London, U.K. Mental Health Group, University of Southampton
Retrospective Studies of NDEs
"The phenomena reported during NDEs included 66 percent who reported an out-of-body experience, 76 percent pastoral landscapes, 38 percent seeing deceased friends and relatives, 12 percent life reviews, 24 percent a barrier of some sort, and 72 percent a decision to return. Only 4 percent had hellish experiences."
http://www.iands.org/research/fenwick1.php
Hmmm, interesting. Now if you add the 24% of barrier+ 4% hellish experience = 28%, not too far from 33%. The 4% is not far from the %age of the general population that are hardened criminals, every culture, throughout history; nothing you can do but lock them away. Anyway, for most folks dying is just moving on to a more pleasant experience, at least until JUDGEMENT DAY. Thanks for your research.