\begin{table}%t11
%\centering
\par
\caption{Mean and standard deviation ($\sigma$) 
of the photon index in the 0.3--2~keV and 2--5~keV energy ranges.
NLG: Narrow Line Galaxies (${\it FWHM}<2000$~km~s$^{-1}$), RQQ: radio-quiet quasars, and
RLQ (radio-loud quasars).\label{tab:mean}}
\begin{tabular}{ccc}
\noalign {\smallskip}  
 \hline
\hline
 Type                           &        0.3--2~keV              & 2--5~keV\\
\noalign {\smallskip}  
 \hline
\noalign {\smallskip}  
All objects                   &    2.56 ($\sigma$:0.44)    &  1.99 ($\sigma$:0.31) \\
\noalign {\smallskip}  
NLG                             & 3.04 ($\sigma$:0.42)          &  2.37  ($\sigma$:0.11) \\
\noalign {\smallskip}  
RQQ                            & 2.43 ($\sigma$:0.35)          &  1.90  ($\sigma$:0.27) \\
\noalign {\smallskip}  
RLQ                            & 2.29 ($\sigma$:0.04)           & 1.74 ($\sigma$:0.03)   \\
\hline
\end{tabular}
\end{table}