\begin{table}%t6
\caption{\label{table:sourcedistribution}Distribution of morphology.}
\small%%\centering

\par
\begin{tabular}{lrr}
\hline\hline\noalign{\smallskip}
{Structure\tablefootmark{a} } & 
{Number} & 
{\%} \\
\hline
SS  & 36 & 84 \\
C   &  1 &  2 \\
DS  &  5 & 12 \\
Irr &  1 & 2 \\
\hline
\end{tabular}
\tablefoot{\tablefoottext{a}{Classification of the structure, as follows: (C) compact,
(SS)~single-sided, 
(DS) double-sided, 
or (Irr) irregular.}}
\end{table}