\begin{table}%t1
%\centering
\par
\caption{\label{tempimedi}The average time  $\left\langle t_{\rm total}\right\rangle $~[Myr]. }
\small
\begin{tabular}{cccc}
  \hline\hline
& 4 kpc   & 8 kpc &12 kpc\\
  \hline
  10 SNe& 43  & 53 &75\\
% &  &  \\
 50 SNe&36&54&87\\
% &  &  \\
 100 SNe& 36 & 57& 96\\
% &  &  \\
 500 SNe& 38 & 75& 133\\
% &  &  \\ 
 \hline
 \end{tabular}
\end{table}