\begin{table}%t2
\caption{\label{estadishistogramas}Median, standard deviation, and number of data points for the distributions of the different groups and line ratios.}  
%%\centering

\par
\begin{tabular}{cccccccccccccccccccccccccc}
\hline \hline \noalign{\smallskip}
Group &
\multicolumn{3}{c}{$\log$(\nha)} &
\multicolumn{3}{c}{$\log$(\sha)} & 
\multicolumn{3}{c}{$\log$(\oha)}  \\
 &
Median & Std Dev & $N$ &
Median & Std Dev & $N$ &
Median & Std Dev & $N$ \\
\hline
All     & $-0.37$ & 0.18 & 24~017 & $-0.49$ & 0.16 & 12~564 & $-1.46$ & 0.34 & 5733\\
Class 0 & $-0.37$ & 0.18 & 10~605 & $-0.55$ & 0.13 & 4932  & $-1.56$ & 0.28 & 1953\\
Class 1 & $-0.38$ & 0.17 & 6680  & $-0.49$ & 0.18 & 3140  & $-1.43$ & 0.33 & 1349\\
Class 2 & $-0.36$ & 0.16 & 3992  & $-0.48$ & 0.17 & 2628  & $-1.35$ & 0.35 & 2023\\
\hline
\end{tabular}
\vspace*{6.5mm} 
\end{table}