\begin{figure}[!h]\small
\begin{center}
\begin{tabular}{|r|r|r|r|r|}\cline{3-4}
 \multicolumn{2}{c}{~}& \multicolumn{2}{|c|}{Time in seconds} & \multicolumn{1}{c}{~}\\\hline
dataset     & Instances & {\W}1     & {\W}2     & {\W}2 speedup\\\hline
telecom    & 18        & 0.07  & 0.04 & 1.6x\\
coc81       & 63        & 0.43  & 0.08 & 5.3x\\
nasa93      & 93        & 0.69  & 0.10 & 6.6x\\
china	    & 500       & 7.37  & 0.42 & 10.8x\\\hline
\end{tabular}

~\\

\includegraphics{speed.pdf}

\end{center}
\caption{Average execution times for $Steps1{\ldots}Steps5$ of the
{\W} and {\W}2 algorithms (mean
values in 100 repeats). }
\label{fig:w2-runtimes}
\end{figure}
