\begin{table}%t2
\caption{Mean spectral properties. Col.~I: Spectral parameter; Col.~II: Seyfert~1 mean value; Col.~III: Seyfert~2 mean value; Col.~IV: Probability that Seyfert~1 and Seyfert~2 are drawn from the  same parent populations.}\label{tab2}
\small%\centerline
 {
\begin{tabular}{ l c c c c }
\hline
\hline
Parameter & Tot. & Seyfert~1 & Seyfert~2 & $P_{\rm null}$ \\
\hline
$\Gamma$ & $1.84\pm0.03$  & $1.89\pm0.03$ & $1.80\pm0.05$ & 90\% \\
$R$ & $1.01\pm0.09$ & $1.23\pm0.11$& $0.87\pm0.14$ & 5\% \\
$E_{\rm c}$$^{\dagger}$& $287\pm24\phantom{0}$& $230\pm22\phantom{0}$& $376\pm42\phantom{0}$& 5\% \\
$N_{\rm H}$$^{\ddagger}$ &$31.7\pm9.1\phantom{0}$ & $3.66\pm2.34$ & $61.3\pm18.0$&$\leq$0.1\% \\
\hline
\end{tabular}}
\medskip
$^{\dagger}$ In units of eV; $^{\ddagger}$ in units of 10$^{22}$~cm$^{-2}$.
\end{table}