The question you ask is complicated and the answers are found in many research reports. The problem being, different researchers are studying different aspects of safety. There are different things people are measuring. Of course, much of this depends on what the person conceptualizes safety as- For example, the NNDQI is a large database that tracks nurse sensitive outcomes and has data such as falls etc. So, for some people falls are one aspect of safety. For other people, safety is a medication error or preventing a near miss. I think your best investigation in to this complicated problem is to look at National Institutes of Health, AHRQ, and Institute for Healthcare Improvement, along with Joint Commission. All of these organizations have statistics.
I am highly supportive of the comments by Wendy Kooken. Additionally, I would be interested in whether you are seeking information on Quality and Safety in Healthcare as a whole, or whether there are specific professional disciplines (medicine, nursing, paramedicine, physiotherapy) which you are interested in?
There are some good resources on Australian websites which I am happy to talk you through - see the New South Wales Clinical Excellence Commission [http://www.cec.health.nsw.gov.au/publications] , and the Australian Commission on Safety and Quality in Health Care [http://www.safetyandquality.gov.au/].
Do these reports in paper or you have these reports in the system (electronic reporting system)? This will allow to compare your institute metric longitudinal for 5 years.. If you and professionals commented in this discussion interested to do research together on this I would be grateful??