\begin{table}%t5
\caption{\label{tab:relat_tri}Minimum,   maximum    and   average chromaticity  of  tricoupler  splitting  ratio  (among  the  three outputs   of   each  tricoupler).    $T_{1}$~is  the   tricoupler corresponding to input~1.} 
%\centering
\small
\begin{tabular}{c|c c c }
\hline
\hline
Tricoupler & Average & Minimum & Maximum \\
\hline
$T_{1}$ & 8\% & 3\% & 12\% \\
$T_{2}$ & 13\% & 6\% & 19\% \\
$T_{3}$ & 13\% & 3\% & 19\% \\ 
$T_{4}$ & 9\% & 5\% & 14\% \\ 
\hline
\end{tabular}
\end{table}