Present estimates of Lyman continuum photon production efficiency ξ_ion, 0 vs. absolute UV luminosity M_UV. The red dashed line denotes the lower limit for the population-averaged ξ_ion, 0 obtained by making the extreme assumption that all sources in UV selections not appearing in our MUSE selections have ξ_ion, 0 = 0 (see Sect. 4.4 for details). For comparison, also shown here are several previous estimates of ξ_ion, 0 by Bouwens et al. (2016a) at z = 3.8–5.0 (light magenta) and z = 5.1–5.4 (dark magenta; using a revised binning, see Sect. 5.1.), Harikane et al. (2018) at z = 4.9 (orange), Matthee et al. (2017) at z = 2.2 (Meurer et al. 1999β-dust correction, green), and Shivaei et al. (2018) at z = 1.4−2.6 (SMC dust correction, blue). The black dashed line denotes the best-fit M_UV dependence of ξ_ion, 0 on M_UV using the measurements of Bouwens et al. (2016a) and this work. The best-fit relation is ξ_ion, 0 = 0.020(±0.031)(M_UV + 20)+25.372(±0.045).