I get about 2.5 per thousand although to be honest these numbers won't help you much.
You have so many variables, like areas you delievr, who delivers, offers, solus or multiple leaflets per drop that it's a waste of time asking the question.
For instance say someone does high end, delivers via a third party who delivers 3-4 leaflets and get 1 response per thousand. Crap you say.
Another guy hand delivers just his leaflet to his neighborhood, has a nice leaflet on glossy paper and gets 3 jobs per thou. Obvious which is best yeah?
No, cos the first one has figured out his average job price is £300 and the other guy gets £60!