\begin{table}%t3
    %\centering
\par
      \caption{Averaged warm absorber parameters for the sources in Table~\ref{phase_properties}: object name, range in log ionisation parameter ($\Delta$ log $\xi$; erg s$^{\rm -1}$), log total equivalent hydrogen column (log $N_{\rm Htot}$; cm$^{\rm -2}$), log weighted average ionisation parameter (log $\xi$$_{\rm avg}$; erg~s$^{\rm -1}$), weighted average outflow velocity ($v_{\rm avg}$; km~s$^{\rm -1}$).}
         \label{average_properties}  
   %\centering
\par
         \begin{tabular}{llllr}
            \hline\hline
            \noalign{\smallskip}
Object     & $\Delta$ log $\xi$ & log $N_{\rm Htot}$ & log $\xi$$_{\rm avg}$ & $v_{\rm avg}$  \\
            \noalign{\smallskip}
            \hline
            \noalign{\smallskip}
MR2251-178      & 2.22    & 21.54 & 2.87 & 250 \\
PG~0844+349      & 0       & 23.6  & 3.7  & 63~000 \\
PG~1211+143      & 4.3     & 23.77 & 3.39 & 24~000 \\
IRAS 13349+2438 & 2.25    & 22.34 & 2.21 & 30 \\
NGC~4593        & 2.11    & 21.82 & 2.54 & 204 \\
NGC~3783        & 1.8     & 22.58 & 2.68 & 750 \\
Markarian 509   & 0       & 21.3  & 1.76 & 200 \\
NGC~7469        & 4       & 20.60 & 2.1  & 800 \\
NGC~3516        & 0       & 21.9  & 0.78 & 200 \\
NGC~5548        & 2.29    & 21.92 & 2.51 & 362 \\
MCG -6-30-15    & 1.25    & 21.60 & 2.22 & 1025 \\
Markarian 766   & unknown & 21.2  & 0.7  & 0   \\
NGC~4051        & no info & 21    & 1.4  & 402 \\
Ark 564         & 2       & 21.30 & 1.70 & 150 \\
            \noalign{\smallskip}
            \hline
         \end{tabular}        
  \end{table}