Experiment	Measurement	Reference
Belle	\([2.12 \pm 0.16\mbox{ (stat)} \pm 0.18\mbox{ (syst)}] \times 10^{-4}\)	PRD 85 (2012) 091106
BaBar	\([2.8 \pm 0.4\mbox{ (stat)} \pm 0.3\mbox{ (syst)} \pm 0.4\mbox{ (correlated syst)}] \times 10^{-4}\)	PRD 73(2006) 112004
Average	\(\mathbf{[2.20 \pm 0.23\mbox{ (combined)}] \times 10^{-4}}\)