The American Alpine Club publishes Accidents in North American Mountaineering (abbreviated throughout this site as ANAM) annually. It's a highly informative read of the accounts of incidents, with analysis and comment. In the appendeces, the statistical tables categorize the myriad ways that people got the chop. You can find ANAM in your local library, or order it online from any number of book suppliers.
Many years ago I read in this journal, or one like it, that 75% of all "climbing" accidents occur during the descent.