Your SOC tracks endpoint telemetry health across three business units of very different sizes: BU-A has 12,000 hosts, BU-B has 2,500 hosts, and BU-C has 300 hosts. Leadership wants a single coverage dashboard that fairly compares how well each business unit is delivering endpoint process-event telemetry, and flags units that are under-reporting relative to expectations. Raw daily event counts show BU-A dominating simply because it has more hosts. Which metric should you present as the primary comparison to fairly identify under-reporting units?