 Review of Particle Physics by Particle Data Group (2021)

Official edition: pdg.lbl.gov/2021/

Tau lepton listing: pdg.lbl.gov/2021/listings/rpp2021-list-tau.pdf

Z boson listing: pdg.lbl.gov/2021/listings/rpp2021-list-z-boson.pdf

The tau lepton listing gives the electronic branching fraction on page 6. The Z boson listing gives the hadronic-to-single-lepton partial-width ratio on page 9.