The following works for me:

\begin{table}[htdp]
\begin{center}
\begin{tabular}{|c|c|c|}
\hline
& PatAddTTCoord & AddTTClusterTool\\
\hline
hit-efficiency\footnotemark & 93.2 \% & 90.6 \% \\
\hline
\end{tabular}
\end{center}
\label{tb:comp1}
\end{table}%
 
\footnotetext[\value{footnote}]{Hit-efficiency is defined in section \ref{sec:effdef}}