Customs keeps statistics covering shipments reviewed, how many were high-risk, how those were examined (non-intrusive only, non-intrusive plus physical, physical only), clearance times, and findings both positive and negative; reports on SAFE implementation go to the WCO, high-risk statistics are shared between Customs where appropriate, and tools such as the Time Release Study support evaluation.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.