In spite of notable progresses achieved at BNL and KEK during last decade, a consistent understanding of nonmesonic weak decay (NMWD) of \Lambda hypernuclei is yet to be achieved. Until recently, all the experimental data since the days of bubble chamber and emulsion showed the dominance of the neutron induced channel (\Gamma _n) over the proton induced one (\Gamma _p) in the NMWD of \Lambda hypernuclei, while the theoretical calculation predicted the predominance of the proton induced one. This inconsistency has been known as the famous `\Gamma_n/\Gamma_p puzzle' and the central focus in the study of the decay mechanism of the \Lambda hypernuclei and the baryonic weak interaction. However, important progresses have been made recently in both the experimental and theoretical sides. In this paper, the progresses in the experimental data on NMWD will be presented. The direct comparison of the recent proton and neutron spectra showed the \Gamma_n/\Gamma_p ratio, 0.45\sim 0.51\pm 0.15(stat.) much less than unity. This ratio agrees well with the recent theoretical calculations. Though this outcome seems to indicate that the famous long standing puzzle has almost been resolved, the decay asymmetry still remains to be understood.

PACS numbers: 21.10.Tg, 21.30.Fe, 21.80.+a, 24.10.Lx