A Study of Freely Forming Groups in Bars Throughout Europe

Short Answer

A study of freely forming groups in bars throughout Europe examined the number of individuals found in groups that were laughing together. A summary of the 501 groups examined is shown here:
$$\begin{array} { | l | l | } \hline \text { Group size } & \text { Number of groups } \\\hline 2 & 254 \\\hline 3 & 168 \\\hline 4 & 52 \\\hline 5 & 21 \\\hline 6 & 6 \\\hline\end{array}$$ What is the median group size?