\begin{table}%t3
%\centering
\par
\caption{Tabulated AGN number counts as a function of $R$~band 
magnitude. The~2nd and~4th column give the actual numbers of
objects in the current COMBO-17 sample (within 0.78~deg$^2$), 
while the~3rd and~5th column give incompleteness-corrected 
surface densities per~deg$^2$.\label{tab:surfdens}}
\begin{tabular}{r@{\hspace*{2.5em}}rr@{\hspace*{2.5em}}rr}
\hline \hline
\noalign{\smallskip}
        & \multicolumn{2}{c}{$z > 1.2$\hspace*{2.5em}} &
          \multicolumn{2}{c}{$z > 2.2$\hspace*{0.5em}} \\
$R$ & \multicolumn{1}{c}{$n$} & \multicolumn{1}{c}{${\cal N}(<R)$\hspace*{1.8em}} &
      \multicolumn{1}{c}{$n$} & \multicolumn{1}{c}{${\cal N}(<R)$} \\
\noalign{\smallskip}\hline\noalign{\smallskip}
24.0 & 192 & 336.5 & 101 & 201.7 \\
23.0 & 139 & 183.2 &  60 &  79.5 \\
22.0 &  86 & 107.7 &  33 &  41.8 \\
21.0 &  43 &  55.1 &  16 &  20.5 \\
20.0 &  18 &  23.1 &   8 &  10.3 \\
19.0 &   8 &  10.3 &   2 &   2.6 \\
18.0 &   2 &   2.6 &   1 &   1.3 \\
\hline
\end{tabular}
\end{table}