Population-average [CII]-to-IR luminosity ratios, derived comparing our [CII] constraints with integrated IR luminosity function of Gruppioni et al. (2013). Red limits and pink crosses indicate 3σ upper bounds and 1σ intervals in each redshift bin. Purple bars show the variance-weighted average over all bins (z ∼ 0.33 − 2.9), with dark purple and light purple indicating 1σ and 2σ intervals. We also show the average ratios for local SFGs from [CII] observations from Accurso et al. (2017), and for LIRGs and ULIRGs from Díaz-Santos et al. (2017).