The answer was 18.

They are the clubs with foreign (not British or Irish - yes deal with it) managers.

This might support the view that British (and Irish) coaches aren't as good as their foreign counterparts.
The exception being Zola who is undoubtedly crap, but then he has done almost all of his coaching in the UK.

Doesn't apply to Warnock of course, who has transformed us. He is limited but understands that and is able to play to his own strengths.