I have the table of this code. When I insert this table, the text is very small and I dont see a lot. How can I insert this table for a better comprehension of the text?
\begin{table}[h]
\begin{center}
\begin{tabular}{ | l | c | c | c | c | c | c | c | c | c | c | c | c | c | c | c | c | }
\hline
\multirow{2}{*}{\textbf{Method Function}} & \multirow{2}{*}{Lineal} & \multicolumn{4}{c|}{Pol} & \multicolumn{5}{c|}{Gaussian} & \multirow{2}{*}{S method} & \multirow{2}{*}{Line} & \multirow{2}{*}{Upload} & \multirow{2}{*}{Fourier} & \multirow{2}{*}{Marconi} & \multirow{2}{*}{Tesla} \\
\cline{3-11}
& & grade 1 & grade 2 & grade 3 & grade 4 & $\sigma=0.15$ & $\sigma=0.25$ & $\sigma=0.5$ & $\sigma=2$ & $\sigma=3$ & & & & & &\\
\hline
Template & 57\% & 80\% & 92 & 89 & 89 & 94 & 97 & 97 & 94 & 92 & a & b & c & d & e & f \\
\hline
Template & 57\% & 80\% & 92 & 89 & 89 & 94 & 97 & 97 & 94 & 92 & a & b & c & d & e & f \\
\hline
\end{tabular}
\end{center}
\end{table}