\begin{table}
\begin{center}
\begin{tabular}{|c|r|r|}
\hline
\multicolumn{1}{|c|}{A} & \multicolumn{1}{c|}{BB} & \multicolumn{1}{c|}{CCC} \\
\hline
DDD      &   E           & FF${}^1$     \\ \hline
GG       & HHH${}^2$     & I            \\ \hline
%\multicolumn{3}{l}{${}^1$ ~Kr~R~M}\\
%\multicolumn{3}{l}{${}^2$ ~Kr~R~M2}
\end{tabular}
\caption{test}
\end{center}
\end{table}