Histogram of the L_X/L _{[O IV]}  ratio of the data points shown in Fig. 1. The red dashed line represents Sy2 non-masers, whereas the blue thick line represents the Sy1 non-masers. The maser-detections are represented by the dashed surfaces – blue and vertically dashed for Sy1, red and horizontally dashed for Sy2. The one upper limit is excluded.