\begin{table}%t9
%\centering
\par
\caption{\label{costats}Statistics of CO emission in the $\sigma$-drop and
control samples. All data are in units of $10^{54}$~W~km~(Hz~s)$^{-1}$.}
\begin{tabular}{l c c c }
\hline\hline
Sample & Mean & Median & Std. deviation\\
\hline
$\sigma$-drop & 52.1 & 40.7 & 48.9\\
control & 39.5 & 30.9 & 35.5 \\
\hline
\end{tabular}
\end{table}