Cumulative number counts normalized to the Euclidean slope (multiplied by S) for HGL sample with detection significance level  ≤ 2 × 10^-5 in the soft band (0.5–2 keV, red filled circles, left panel) and in the hard band (2–10 keV, red filled circles, right panel). Other symbols represent: the C-COSMOS curve (blue open circles, Elvis et al. 2009), the XMM-COSMOS curve (black filled squares, Cappelluti et al. 2009), the Moretti et al. (2003) compilation (blue dashed line), the soft band curve of Hasinger et al. (2005; green dashed line), the CDF-N (magenta dotted line, Alexander et al. 2003) and the CDF-S (cyan solid line, Luo et al. 2008) curves, the Mateos et al. (2008) compilation (cyan solid triangles).