Share of 2,473 percentage claims that land on a multiple of 5, split by provenance tier. Unattributed 41.7% (95% CI 37.7–45.7), Sourced 36.7% (33.7–39.9), First-party 24.6% (22.0–27.5). Overall 33.2% versus a 20.8% chance baseline. Wilson 95% intervals; deterministic, zero-LLM. N = 2,473.