\begin{table}%t2
\caption{\label{omegat}The cosmological mass density of neutral gas in DLAs from this work (SDSS-DR7).}
%\centerline
{\small
\begin{tabular}{c c c l}
\hline\hline\noalign{\smallskip}
$z$        & $\avg{z}^a$  & $\Delta X$ & $\omegagdla$ ($\times 10^{-3}$) \\
\hline     
2.23--2.60  & 2.44  &  2774      &   $0.82\pm0.09$	\\
2.60--2.88  & 2.74  &  2774      &   $0.85\pm0.09$	\\
2.88--3.20  & 3.02  &  2774      &   $1.03\pm0.10$	\\
3.20--5.19  & 3.49  &  2774      &   $1.29\pm0.15$	\\
\hline
\end{tabular}}\smallskip
\par
$^a$ Median redshift corresponding to half the total pathlength $\Delta X$ in the redshift bin.
\end{table}