Layout of nx2 figure which use the maximal available space

Layout of nx2 figure which use the maximal available space

Is it normal that the following figure places the four images below each
other instead of in a 2x2 matrix?
\begin{figure}
\centering
\includegraphics[width=0.5\textwidth]{eval1.pdf}
\includegraphics[width=0.5\textwidth]{eval2.pdf}
\\
\includegraphics[width=0.5\textwidth]{eval3.pdf}
\includegraphics[width=0.5\textwidth]{eval4.pdf}
\caption{Results for four scenarios}
\label{results}
\end{figure}
When I use 0.49\textwidth instead if works as expected, but to me this
looks like a hack and becomes somewhat tedious when using 3x2 or 6x2
layouts...
Is there any elegant way to layout multiple images like that? Like saying
use x% of the maximal available width for theses n images.