Define "end badly".
I ask because my personal definition of "end badly" means an innocent bystander hurt or killed. I don't consider situations where the police utilize the PITT maneuver or spike strips etc and cause the fleeing individual to wreck to be "ending badly".
From "An Introduction to Policing - John S Dempsey" Miami/Dade County study of 952 pursuits in their Metro area: 38% (361) ending in accidents. 17% (160) resulting in injuries, 0.7% ending in death. Of the 160 injuries, 30 involved injury to a police officer, 17 to an innocent bystander, 113 to a fleeing individual or passenger.
So in my line of thinking, I'm bothered by the 17 innocent bystanders injured. The 113 fleeing individuals I would consider those injuries self inflicted, and while I do feel for the 30 police officers who were injured, it's a risk of the job, although an unfortunate one. The death was not categorized in the text, so I'm unaware if it was police, fleeing individual, or 3rd party.
Of the 952 chases studied, 54% were initiated due to traffic violations, 2% for reckless/impaired driving, 33% for "Serious criminal activity" (as an aside, while reading this study I could not find a definition of "Serious criminal activity" although I'd assume it essentially means "felony") and 11% were answering BOLO (Be On Lookout) calls.
So, based on this study, injuries occur at all somewhere in the area of 20% of the time, and the vast majority of those times the injured person will be the fleeing individual. Police involved in the chase come in a distant second.
FWIW, there is no link to the study because I had the referenced title in my library, I did find the title on Google Books however.
An Introduction To Policing p252.