Notes:

Well that depends. It depends first of all on the definition of PTSD you use. You can now begin to see the usefulness of even the procrustean use of diagnostic criteria.

There was no DSM after the world wars, 85% of survivors of one Nazi concentration camp were judged to have concentration camp syndrome and none were thought to be without symptoms. It seems perhaps not surprisingly now to depend greatly on the type and the duration of the stressor. Only 57% of Coconut Grove survivors had multiple symptoms.

It also seems linked to severity of the stressor so that there is a difference in the prevalence in Vietnam vets depending on their level of exposure to combat. Notice though they didn’t have to see active combat to get the symptoms.

I’ve also put up the results of one large US house to house survey of the general population, and as you can see it is a relatively rare disorder overall. Though since you need to have a house to be counted in a house to house survey and since if you loose your job your house might be next, it could be that the house to house survey underestimates the prevelance.