\begin{table}%T1
\caption{Best fit values of the parameters of the evolutionary
models for canonical radio sources.}\label{tab:parameters}
%\centering
\par
\begin{tabular}{lcrrccrr}
  \hline\hline
Source type &\multicolumn{4}{c}{Luminosity function}&\ &
\multicolumn{2}{c}{Evolution}\\ \cline{2-5} \cline{7-8}
\noalign{\smallskip}
 & \multicolumn{1}{c}{$\log n_0~(\hbox{Mpc}^{-3})$}
 & \multicolumn{1}{c}{$a$}& \multicolumn{1}{c}{$b$}&
 \multicolumn{1}{c}{$\log
 L_\ast~(\hbox{erg}~\hbox{s}^{-1}~\hbox{Hz}^{-1}@5~\hbox{GHz},z=0)$} & \
 & \multicolumn{1}{c}{$k_{\rm ev}$} & \multicolumn{1}{c}{$z_{\rm top}$} \\
\hline
FSRQ    & $-$8.988 & 0.651 &  2.888 & 34.043 & & 0.224 & 2.252 \\
BL Lac  & $-$7.921 & 0.977 &  1.266 & 32.789 & & 0.745 &       \\
Steep   & $-$8.030 & 1.071 &  3.054 & 33.329 & & 4.902 &       \\
 \hline
\end{tabular}
\end{table}