Experiment	Measurement	Reference
CDF	\([6.6 \pm 1.9\mbox{ (stat)} \pm 1.1\mbox{ (syst)}] \times 10^{-4}\)	PRL 88 071801 (2002)
Average	\(\mathbf{[6.6 \pm 2.2\mbox{ (combined)}] \times 10^{-4}}\)