Hope you like them (I did them!)
Louise those kind of figures are for huge regional or even national mailings (and they'd bite your hand off for 1 response out of 100, it's
lot less than that for huge campaigns, I used to run them!).
For a few hundred leaflets around your local area, there's no real statistics. Some do really well, some don't do as well. It's all anecdotal really
There's only one real way of knowing, and that's by trying it a couple of times.
But you're right about the web and Faecbook, the idea is that you tie a leaflet campaign in to digital campaigns too. i.e. you use the leaflet to drive people to the web/facebook page.
The difference being a leaflet campaign is pro-active (i.e. you're reaching out to people) and websites and Facebook are reactive.