Variation in obscured fraction with source X-ray luminosity in CDFS and COSMOS. The ratio is A₂/(A₁ + A₂), where A₁ and A₂ are the numbers of type-1 and type-2 sources, respectively. Here, the two samples are considered together as one. The top left panel considers the whole AGN sample, while the other panels consider, respectively, z < 0.89 (top right), 0.89 ≤ z < 1.57 (lower left), and z ≥ 1.57 (lower right) AGN. A moving bin is used as described in Fig. 1. Light-grey shaded regions show the associated statistical error, while dark-grey shaded regions show tentative completeness levels for the CDFS (at low luminosities) and COSMOS (at high luminosities) samples accounting for column densities of up to log (N_H [cm^-2] ) = 24 (see text). The horizontal dotted line shows the overall A₂ fraction in each case, .