Over the past 3 years, a cloud service has been unavailable for a total of 33 hours, primarily due to a denial of service attacks. Additionally, the physical server hosting the cloud service crashed repeatedly and the cloud provider was down 26 days over the same 3 year period of cloud service operation. Based on these statistics over the past 3 years, what is the availability rating of the cloud service?

Please provide all calculations and your reasoning behind each step.