Distribution of neutral hydrogen column density log(N_H) (left panel) and hardness ratios (HRs; right panel) for AGNs selected using the MEx diagram. Objects that do not show absorption are plotted at HR = 1, and are represented with a solid line histogram in the left panel. The dotted vertical lines at log(N_H) = 22 and HR = −0.2 indicate the adopted dividing lines between obscured and unobscured AGNs.