Marginalized posterior distributions at 68% and 95% C.L. for the two parameters α_M0 and β of the exponential evolution, Ω(a) = exp(Ω₀a^β)−1.0, see Sect. 5.2.1. Here α_M0 is defined as Ω₀β and the background is fixed to ΛCDM. Ω_M0 = 0 corresponds to the ΛCDM model also at perturbation level. Note that Planck means Planck TT+lowP. Adding WL to the data sets results in broader contours, as a consequence of the slight tension between the Planck and WL data sets.