Fortunately, zero. I don't even like to think about it.
(Successfully doing the Heimlich maneuver once on someone in a restaurant was close enough for me, as far as your question. And, funny -- at that time when it was happening, I do not even remember my emotions. It's thinking about it afterwards that can get to me. Don't know why I went off topic there.)
A few times and once I almost did something real punky and fainted from finding a nasty injury on a injured worker. Glad I now work at jobs were the worst I will see is a bee sting. Cheers and happy weekend!