Zero - Thank personal responsibility and thinking ahead.
First, get a new unlisted number.
Second, never give your number out -- 90+% of "contests" that you sign up for are just out to get your personal info. They are literally "info farming" and the prize they give out (IF) is well worth the amount of info they farm.
Third, if people are calling your number asking for the person who had it previously, explain that this is no longer their number, but the number for a Catholic monastery, you have all taken a vow of poverty (or make up your own lie) and please take your number off their list.
I haven't had any cold calls in years because of this. I have received a call or two from Sears because I have an account there, but after I told them to stop, they did. Now, I'm never bothered by anyone except my GF's mother.