\begin{table}%t1
%\centering
\par
\caption{The hard X-ray sample.}\label{tab:samp}
\begin{tabular}{@{}lccccccc@{}}
\hline\hline
Survey       &Solid angle& $S_{\rm lim}$&$N_{\rm tot}$&$N_{\rm unid}$&$N_{\rm zph}$&$N_{\rm AGN1}$&$N_{\rm AGN2}$ \\
             & [deg$^2$] &[erg cm$^{-2}$ s$^{-1}$] &               &                &               && \\
\hline 
HEAO1/Grossan    & 2658--22~000  & (1.0--2.7)   $\times$ 10$^{-11}$ &   50 &   0 &   0 &  41 &   9\\
AMSS/ALSS    & $\sim$4.8--90.8  & (0.11--2.1)  $\times$ 10$^{-12}$ &  139 &   1 &   0 &  88 &  37\\    
HBSS         & 25.17            & 2.15 $\times$ 10$^{-13}$         &  67 &  2 &   0 & 42 &  20\\  
XMS          & 2.46--3.80       & (3.30--9.36) $\times$ 10$^{-14}$ &  144 &  13 &   0 & 111 &  25\\  
CLASXS       & 0.4              &          1.3 $\times$ 10$^{-14}$ &  112 &  19 &   0 &  67 &  41\\   
HELLAS2XMM   & 0.21--0.90       & (1.0--3.7)   $\times$ 10$^{-14}$ &  171 &  27 &   0 &  115 &  51\\
SEXSI        & 0.046--0.979     & (0.51--5.72) $\times$ 10$^{-14}$ &  252 &  40 &   0 & 151 &  90\\ 
LH/XMM       & 0.1056           & 5.1          $\times$ 10$^{-15}$ &   64 &   4 &  11 &  40 &  20\\
CDF-S       & 0.012--0.0873    & (0.44--1.49) $\times$ 10$^{-15}$ &  239 &   4 &  66 &  80 & 131\\
CDF-N       & 0.0075--0.0873   & (0.18--1.49) $\times$ 10$^{-15}$ &  284 &   8 & 111 &  99 & 141\\
\hline
Total        &                  &                                 & 1406 & 112 & 188 & 759 & 531\\   \hline
\end{tabular}
\end{table}