Histogram of the integrated R₃₂ for the five QSO2s for which CO(2–1) and CO(3–2) transitions are available. They are shown as filled purple bars. The values measured for a sample of QSO2s at z < 0.2 from Molyneux et al. (2024) are also shown in light blue, for the X-ray selected AGN reported by Lamperti et al. (2020) in pink, of the local ULIRGs presented in Montoya Arroyave et al. (2023) in yellow, and the mean value measured for star-forming disk galaxies from Leroy et al. (2022) is the gray dot-dashed line, with the corresponding interval shown as a shaded gray area.