How many of the airliners that ever existed have been lost in flight?
Okay, let's try for a first approximation. Some heavily-produced airliners; for simplicity I'm only counting jets. (ie, I don't want to try and work out how to deal with the DC-3...)


A320 family. 7481 built, 35 hull losses (0.5%)
A330. 1330 built, 11 hull losses (0.8%)
Boeing 727. 1832 built, 118 hull losses (6.4%, mostly out of service)
Boeing 737. 9401 built, 184 hull losses (2.0%)
Boeing 747. 1528 built, 60 hull losses (3.9%)
Boeing 757. 1050 built, 8 hull losses (0.8%)
Boeing 767. 1097 built, 15 hull losses (1.4%)
Boeing 777. 1467 built, 6 hull losses (0.4%)
DC-9. 976 built, 101 hull losses (10.3%, mostly out of service)
MD-80. 1191 built, 35 hull losses (2.9%)
Tu-134. 854 built, 69 hull losses (8.1%, mostly out of service)
Tu-154. 1026 built, 69 hull losses (6.7%, mostly out of service)


This is a partial list, but it includes (I think?) every type with around 1000 or more examples built. It is thus probably representative of the general population of jet airliners. Total 29,322 aircraft, of which 711 (~2.5%) were eventually hull losses.

Now, not all hull losses are flight accidents - there are ground fires, accidents, military action, hurricanes, all sorts of other things - but the majority are. It's probably reasonable to estimate that the overall hull-loss-due-to-flight-accidents-so-far rate is thus a little lower, around 2%, but probably not much below that.

Now, it's worth noting that this isn't quite the same as 


  If you were born as an airliner, what is the probability that you would die at work?


...because some of these aircraft will probably be hull losses, it just hasn't happened yet. If Boeing stopped building 747s tomorrow but airlines kept flying them, the hull loss rate would steadily creep up over time until all examples were either crashed or retired. So if you want to work from that perspective, the "eventual accident rate" will be higher. I've flagged the ones which are nearly completely out of service, where these will be approaching a "lifetime" loss rate - they're noticeably higher than the others.