The z-histograms for CVs. The upper panel shows the z-histogram for all CVs in the sample and the lower panel magnetic systems (mCVs). The blue dashed line represents the ﹩{{\rm{sech}} }^{2}﹩ function and the red solid line the exponential function. The 2D posterior probability distributions of the model parameters sampled by MCMC are demonstrated to the right of the z-histograms.