\begin{table}%t2
%\centering
\par
\caption{Compression rates for different thresholds with or without~map.}\label{xmgrD1p6ech6avecousans}
%\setlength{\tabcolsep}{10pt}
\begin{tabular}{lcccc}
 \hline\hline
 &1.5$\sigma$   &2$\sigma$  &2.5$\sigma$&3$\sigma$  \\
 \hline
Without map&36     &76    &186 &480\\
With map & 37 &80 &209 &670\\[3pt]
\hline
\end{tabular}
\end{table}