Experiment	Measurement	Reference
Belle	< \(3.0 \times 10^{-6}\)	Belle:cref:0727 (superseded)
Belle	< \(3.6 \times 10^{-6}\)	PRL 101, 041601 (2008)
Average	< \(\mathbf{3.6 \times 10^{-6}}\)