What are the ejection injury and fatality rates? Most of us have probably heard about how ejecting from a military aircraft is dangerous in and of itself, and that ejection is not a get out of jail free card.

The most common dangers seem to be:


Lacerations during the ejection, by failing to clear the cockpit.
Concussions caused by collisions with the canopy or fuselage.
Insufficient altitude or speed to deploy a parachute before impacting terrain.
Other assorted hazards associated with parachuting down in an unprepared location.


There exist a number of openly-available reports on the topic, from several different countries and time periods that could serve as a starting point.

I have multiple closely-related questions, so I hope it will be self-evident why I chose not to split them up, but feel free to focus only on the first one:


What are the odds of surviving an ejection from a military aircraft? We can presuppose a fit crew member, but make no further assumptions about the particular case.
How likely is the crew member to sustain injuries?
Are there any significant trends in the data, e.g. introduction of 0-0 seats, survival procedures, sub- vs. supersonic ejection?
Survival outcomes in low level ejections from high performance aircraft is a 2013 consolidation of ten separate studies of ejections from 1952-1997, focused on comparing low level to high level ejections. It doesn't state that these were military (though likely) and only considered those where altitude was known. From the abstract:


  There were 562 low-level ejections identified. Out of this number, there were 274 fatalities, giving a low-level ejection survival rate of 51.2%. There were 2607 ejections that occurred above 500 ft (152 m), with a survival rate of 91.4%. There was a significant difference between ejection survival rates below and above 500 ft (152 m). Low-level ejections have a significantly increased risk of a fatal outcome (Odds Ratio 10.07).


So overall the odds of surviving an ejection are 84%.