Not all of us do. With no statistics anywhere showing DOB and death dates I don't know how anyone can categorically state that any kind of dog is fitter. I think many of the oldest living dogs ever have been pedigrees.

Data may not give an acurate detail of the dogs health but would show if any breed or cross breed lives long lives.

I know! - I (hope) I would not keep a dog alive for my sake...but it does happen...therefore these statistics would not give a true indication of the health of the dog....I must be making a mistake with my writing as I seem to be confusing you with what I am saying.