\begin{table}%t1
\caption{\label{stackall}Mean spectral properties from the stacking analysis of sources in the 3$\sigma$~hard sample detected in the pn at off-axis angle $<$11\arcmin. $N_{\rm H}$ is fixed to the galactic value.}
\small%\centering
\par
\begin{tabular}{lrc}
\hline \hline
Flux bins	& N. of sources	& $\Gamma$ \\
\hline \noalign{\smallskip}
$-14.1 < \mbox{log}~F_{\rm X} < -13.7$	& 25 & $\rm 1.72^{+0.09}_{-0.09}$\\
$-13.7 < \mbox{log}~F_{\rm X} < -13.6$ & 22 & $\rm 1.81^{+0.09}_{-0.08}$ \\
$-13.6 < \mbox{log}~F_{\rm X} < -13.5$ & 15 & $\rm 1.83^{+0.10}_{-0.09}$ \\
$-13.5 < \mbox{log}~F_{\rm X} < -13.3$ & 14 & $\rm 1.76^{+0.08}_{-0.08}$ \\
$-13.3 < \mbox{log}~F_{\rm X} < -12.9$ & 7 & $\rm 1.75^{+0.12}_{-0.12}$ \\
\hline
\end{tabular}
\end{table}