Panel a: mass outflow rate as a function of L_Bol for PDS 456 (red star) and a compilation of AGNs with outflow detection from Fiore et al. (2017), Fluetsch et al. (2019), Zschaechner et al. (2016), Feruglio et al. (2017), Querejeta et al. (2017), Vayner et al. (2017), Veilleux et al. (2017), Brusa et al. (2018), Longinotti et al. (2018), Herrera-Camus et al. (2019). The blue(green) dashed line shows the best-fit parabolic function for the molecular(ionised) phase, while the shaded area indicates the rms scatter of the data from the relation. Panel b: ratio μ = Ṁ_ion/Ṁ_mol (black solid curve) inferred from the best-fit relations in panel a, as a function of L_Bol. The shaded area represents the uncertainty on μ, given the scatter of these relations. Data points indicate the position in the μ − L_Bol plane of the AGNs with available molecular and ionised mass outflow rates (Vayner et al. 2017; Brusa et al. 2018; Herrera-Camus et al. 2019). We also include the sources with AGN contribution to L_Bol >  10% from Fluetsch et al. (2019).