\begin{table}%T2
\caption{\label{tab2}Combined GOODS-S plus GOODS-N sample.  The uncertainties take into
  account cosmic variance and have been computed as described in
  Sect.~4.}
  \small%\centering
\par
\begin{tabular}{lccc}
\hline \hline\noalign{\smallskip}
Sample& $z$ range& $r_0$ [$h^{-1}$~Mpc]& $\gamma$\\
\hline
$f_{24}>20~\mu$Jy&            0.1--1.4& $4.03 \pm 0.38$& $1.51 \pm 0.08$\\
$L_{\rm IR}>10^{10}~L_{\odot}$&     0.1--1.4& $4.31 \pm 0.47$& $1.52 \pm 0.08$\\
$L_{\rm IR}>10^{11}~L_{\odot}$&     0.1--1.4& $5.14 \pm 0.76$& $1.58 \pm 0.10$\cr
$L_{\rm IR}\leq 10^{11}~L_{\odot}$& 0.1--1.4& $3.81 \pm 0.36$& $1.54 \pm 0.08$\cr
\hline
\end{tabular}
\end{table}