Web search shows one row per engine: its name, a bar, the percentage and a count such as 42 of 84 answers. It is the share of that engine's answers where it searched the web before it answered.
How it is worked out
An engine counts only where its stored response says yes or no. If the response cannot show it, or an answer has no stored response, the row reads Not reported. It is never a guess. Hover the "?" for how many answers were left out. The rows follow the period, run, market and engine filters at the top of the page.
Engines that can say today include the ChatGPT app, AI Overviews, AI Mode and Perplexity. Gemini, Grok and Copilot show Not reported.
Where to find it
Overview, Engines tab. With the Perception page on, it is on Competitors, Visibility, above the AI Overview trigger rate.
What to do next
An engine that searches often is one where fresh, well-cited pages can change the answer quickly. See Source details.