There's at least a small skew in the numbers as well. My wife was instructed to perform CPR by a 911 dispatcher on someone she found who had died in their sleep

There's at least a small skew in the numbers as well. My wife was instructed to perform CPR by a 911 dispatcher on someone she found who had died in their sleep, and kept talking her through the instructions until paramedics arrived. I'm assuming this is counted in the broader "survival rate" numbers. That's not to say that the overall message is wrong, but CPR being administered to the dead, or those in medical distress who wouldn't benefit from it, will obviously decrease the overall effectiveness scores.