Top left panel: radio power distribution of the full sample and the detections. The sub-panel below shows the detection rate for each bin of the histogram and the average detection rate (dashed line). Top right panel: radio continuum flux (S_{1.4 GHz}) distribution of the full sample (open bars) and of the detections (grey bars). Bottom left panel: redshift (z) distribution of the full sample of 248 radio sources and of the H i detections. The sub-panel shows the detection rate for each bin of the histogram. Bottom right panel: distribution of the optical depth detection limits of the full sample overlaid with the distribution of the optical depth of the peak of the detected absorption lines.