What percentage of phone calls (to your personal phone) do you answer?
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.
I also answer all calls I get and (usually) call back if they missed me. I actively gave my number to one or two research groups for polls. They call maybe twice per year, so it's alright.
As for scammers, maybe 10% of calls are of that sort and so far I enjoy messing with them when they call.