\begin{table}%t4
      \caption{\label{tab4}Mean  central optical emission strength for barred and unbarred disk galaxies.}
         \small%\centerline
{
\begin{tabular}{l l l l l l }
\hline\hline
1   &2    &3  &4    &5     &6 \\
Type& SA &  SB&    SA& SB& All\\ 
    &   & & {\it EW}($\rm H_{\alpha}+[N_{II}]$)& {\it EW}($\rm H_{\alpha}+[N_{II}]$)& {\it EW}($\rm H_{\alpha}+[N_{II}]$)\\
&  & &($\rAA$)&($\rAA$)&($\rAA$)\\
\hline
  S0  & 6 & 1   & 25.0 $\pm$ 25.0 & 59.76 & 29.9 $\pm$ 21.7 \\
 Sa  & 4   &  6   & 1.8 $\pm$ 1.8 & 13.0 $\pm$ 8.6 & 8.5 $\pm$ 5.3 \\
 Sab & --   &  1   & --   & 8.9 & 8.9 \\
 Sb  & 5& 3 & 33.8 $\pm$ 13.0 & 34.1 $\pm$ 21.2 & 34.0 $\pm$ 10.4 \\
 Sbc~& 5   & 7 & 15.5 $\pm$ 5.4 & 40.8 $\pm$ 10.9 & 30.2 $\pm$ 7.5 \\
 Sc  & 3   &  4   & 43.9 $\pm$ 7.1 & 40.9 $\pm$ 2.9 & 42.2  $\pm$ 3.2\\
 Sp & 2  & 1 &   29.5 $\pm$ 8.4 &  6.35 & 21.8 $\pm$ 9.1 \\
%\\
\hline
\end{tabular}}
\end{table}