The table below shows the number of people sitting at tables in the cafeteria. \begin{tabular}{|c|c|}
\hline
Table & Number of People \\
\hline
1 & 4 \\
\hline
2 & 8 \\
\hline
3 & 12 \\
\hline
4 & 16 \\
\hline
\end{tabular} Which rule describes the pattern shown by the number of people at each table?