Evolution of the cosmic molecular gas density, ρ(M_H2), with redshift. Our results derived directly from the detection of the COLF are shown as the purple points and corresponding uncertainties boxes. The extrapolation of the number density of missing sources in the intermediate and high z bins due to our flux limit is shown in the filled triangles. The ρ(M_H2) for the representative sample of the 6C catalog is indicated in the green box, and for the very bright end of our radio luminosity function (L_1.4 GHz > 3 × 10²⁵ W Hz⁻¹) is shown in the purple star. The light orange boxes indicate the results from the ASPECS LP survey (Decarli et al. 2019) and the dotted box from the COLDz (Riechers et al. 2019). The dark and light blue lines represent the predictions from SPRITZ from all AGN hosts, including SF-AGN and SB-AGN, and the AGN-dominated (only AGN1+AGN2) populations.