You are responsible for the reliability of a high-volume enterprise application. Many users have reported consistent failures with an important part of the application, specifically a data-intensive reporting feature, resulting in HTTP 500 errors. Upon investigation of the application's dashboards, you've identified a significant correlation between these failures and a metric representing the size of an internal queue used for generating reports. Further analysis has traced the failures to a reporting backend experiencing high I/O wait times. You promptly resolved the issue by resizing the backend's persistent disk (PD). Now, you need to establish an availability Service Level Indicator (SLI) for the report generation feature. How should you define it?