From a sample of about 120 000 hadronic Z0 decays, using a technique based on a separation of the different event categories in the boosted sphericity product, the fraction of bbBAR decays has been measured to be 0.219 +/- 0.014 (stat) +/- 0.019 (syst). Using the DELPHI determination of the hadronic Z0 width, this corresponds to a partial width GAMMA(bbBAR) = 378 +/- 42 MeV (in good agreement with the standard model prediction of congruent-to 380 N eV). Combining this measurement with the determinations based on events with high p(t) leptons gives an estimate for the branching ratio of b into leptons at LEP of (11.2 +/- 1.2)%, consistent with previous determinations.
