Experiment	Measurement	Reference
Belle	\([3.4 \pm 0.3\mbox{ (stat)} \pm 0.6\mbox{ (syst)} \pm 0.4\mbox{ (model)}] \times 10^{-4}\)	PRD 69, 112002(2004)
BaBar	\([3.5 \pm 0.2\mbox{ (stat)} \pm 0.2\mbox{ (syst)} \pm 0.4\mbox{ (model)}] \times 10^{-4}\)	PRD 79, 112004 (2009)
Average	\(\mathbf{[3.5 \pm 0.5\mbox{ (combined)}] \times 10^{-4}}\)