I’d say I’m hovering around the 60% mark.
I don’t answer calls from numbers I don’t recognise, unless it identifies someone I’m expecting a call from with the “maybe” thing. I don’t use my phone for work (often). I don’t call people to catch up, I’d rather IM. My mother or my best friend call and I ignore them more often than I probably should.
But really I just don’t like talking on the phone that much.
Overall maybe only like 5–10%. Known numbers always, unknown numbers get iffy when I might be expecting a call from somewhere but don’t have their number saved.