We assemble a large set of 2-10GHz radio flux density measurements and upper limits of 294 different supernovae (SNe), from the literature and our own and archival data. Only 31% of SNe were detected. We characterize the SN radio lightcurves near the peak using a two-parameter model, with tpk being the time to rise to a peak and Lpk the spectral luminosity at that peak. Over all SNe in our sample at D<100Mpc, we find that tpk=10^1.7+/-0.9^days and that Lpk=10^25.5+/-1.6^erg/s/Hz, and therefore that generally 50% of SNe will have Lpk<10^25.5^erg/s/Hz. These Lpk values are ~30 times lower than those for only detected SNe. Types Ib/c and II (excluding IIn's) have similar mean values of Lpk but the former have a wider range, whereas Type IIn SNe have ~10 times higher values with Lpk=10^26.5+/-1.1^erg/s/Hz. As for tpk, Type Ib/c have tpk of only 10^1.1+/-0.5^days while Type II have tpk=10^1.6+/-1.0^ and Type IIn the longest timescales with tpk=10^3.1+/-0.7^days. We also estimate the distribution of progenitor mass-loss rates, M, and find that the mean and standard deviation of log(dM/dt/M_{sun}_yr^-1^) are -5.4+/-1.2 (assuming v_wind_=1000km/s) for Type Ib/c SNe, and -6.9+/-1.4 (assuming v_wind_=10km/s) for Type II SNe excluding Type IIn.