Share is of all 998 commits, so the column does not sum to 100.
One file, tasks.js, appears in more than one commit in four. That is a hotspot. Hotspots are where defects gather, and they are the strongest single predictor of future change — Adam Tornhill's Your Code as a Crime Scene builds its whole method on this signal.
The healthy sign sits two rows below it. test_tasks_rendering.py has 141 touches against the source file's 264 — the test moves when the code moves. Compare header.css at 77, which has no test file near it in this list at all.