\begin{table}%t1
\caption{Model atom summary. The entries for Fe refer actually to 
superlevels and superlines of a generic element representing the whole 
iron group from~Sc to~Ni.}\label{table:modelatomsummary}
%\centering
\par
\begin{tabular}{l r r }
\hline \hline 
\rule[-1mm]{0mm}{4.5mm}Ion   &  No.\ of levels & No.\ of lines \\
\hline 
\rule[0mm]{0mm}{3.5mm}\HeI   &   17            &     55  \\
                      \HeII  &   16            &    120  \\
                      \HeIII &   1             &      0  \\
                      \NII   &   1             &      0  \\
                      \NIII  &   33            &    118  \\
                      \NIV   &   38            &    153  \\
                      \NV    &   17            &     80  \\
                      \NVI   &   1             &      0  \\
                      \CII   &   3             &      2  \\
                      \CIII  &   40            &    224  \\
                      \CIV   &   21            &    140  \\
                      \CV    &    1            &      0  \\
                      \FeIII &    1            &      0  \\
                      \FeIV  &   11            &     49  \\
                      \FeV   &   13            &     69  \\
                      \FeVI  &   17            &    121  \\
                      \FeVII &   11            &     52  \\
                      \FeVIII&    9            &     34  \\
                      \FeIX  &    9            &     35  \\
                      \FeX   &    1            &      0  \\
\hline 
\rule[-1mm]{0mm}{4.5mm}20 ions  &   261        &   1252  \\
\hline 
\end{tabular}
\end{table}