\begin{table}%t1
    \caption{Number of spectral lines from the
    atomic databases. Given are the number of X-ray lines (defined as
    lines with wavelengths $\lambda \le 100$~{\AA}) and the sum of
    all lines over the whole spectral range (up to
    $\lambda \approx 10^7$~{\AA}). In the APED database different entries for
    the same transition are possible. In the last row the number of
    unique lines are specified.}\label{xray_lines}
  %\centering
\par
    \begin{tabular}{lll}
    \hline \hline
      Database        & X-ray lines      & All lines         \\ 
      \hline
      CHIANTI Ver.~3  & $\approx$$12.650$  & $\approx$$45.000$  \\ 
      CHIANTI Ver.~4  & $\approx$$22.350$  & $\approx$$74.500$  \\ 
      APED (total)    & $\approx$$326.000$ & $\approx$$463.200$ \\ 
      APED (distinct) & $\approx$$178.000$ & $\approx$$310.400$ \\ 
      \hline
    \end{tabular}
\end{table}