I am interested in finding the average decay energy of the Tauon. I am interested in the average net decay energy as a function of the known branching ratios of the tauon decay as well as the average actual decay energy in electron volts.
As you may have discovered via the wikipedia link:
The 'bible' of particle data is supplied by the Particle Data Group.
There you'll find reliable up-to-date extensive listings of all known properties of any particle, among which the Tau.