You manage a high-traffic web application with a microservice architecture. The home page displays multiple widgets (e.g., weather, stock prices, news headlines), each fetched from a dedicated microservice. If a microservice fails, the serving thread still renders the page but with missing content. Users tolerate occasional degraded service but expect most content to load reliably. To ensure acceptable user experience, what Service Level Indicator (SLI) should you track for your Service Level Objective (SLO)?