\begin{table}%t2
 \caption{\label{tab:prestellar}The ratio of prestellar cores to the total number of YSOs
     at time $\tau$ for three models and the observations.}
%\centering
\par
\begin{tabular}{l r r r r}
\hline
\hline
Region & M2k4 & M6k2a & M10k2 & Observations \\
\hline
$\rho$ Oph & 0.30 & 0.10 & 0.10 & 0.47 \\
Serpens & 0.79 & 0.06 & 0.74 & 0.39 \\
Taurus & 0.32 & 0.09 & 0.22 & 0.25 \\
Cha I & 0.18 & 0.11 & 0.82 & $<$$0.39$ \\
\hline
\end{tabular}
\end{table}