Extinction-corrected magnitude (top) and redshift (middle and bottom) distributions. At faint magnitudes, most variability-selected sample (green triangles) comes from the newly identified quasars (open dark green triangles). The deep sample (orange circles) from the 36°<α< 42° zone (cf. Sect. 3.3) reproduces the corrected counts well (plain red circles) to g = 21.5, validating the computation of the completeness corrections to this magnitude limit. The deep sample is the only one to extend beyond g = 22.5.