\begin{table}%t1 
%\centering
\par
\caption{\label{number}Increase with time of the number of known QSOs, 
BL Lacs, and Seyfert 1s.} 
\begin{tabular}{rrrl} 
\hline\hline 
QSO & BL Lac & Seyfert 1 & Reference \\ 
\hline 
     202 &       &         & De Veny et~al. (1971)                     \\ 
  2251 &       &     190 & V\'eron-Cetty \& V\'eron (\cite{veron84}) \\ 
  2835 &  73   &     236 & V\'eron-Cetty \& V\'eron (\cite{veron85}) \\ 
  3473 &  84   &     258 & V\'eron-Cetty \& V\'eron (\cite{veron87}) \\ 
  4169 & 117   &     358 & V\'eron-Cetty \& V\'eron (\cite{veron89}) \\ 
  6225 & 162   &     575 & V\'eron-Cetty \& V\'eron (\cite{veron91}) \\ 
  7383 & 171   &     695 & V\'eron-Cetty \& V\'eron (\cite{veron93}) \\ 
  8609 & 220   &     888 & V\'eron-Cetty \& V\'eron (\cite{veron96})\\ 
 11~358 & 357   &  1111 & V\'eron-Cetty \& V\'eron (\cite{veron98}) \\ 
 13~214 & 462   &  1711 & V\'eron-Cetty \& V\'eron (\cite{veron00}) \\ 
 23~760 & 608   &  2765 & V\'eron-Cetty \& V\'eron (\cite{veron01}) \\ 
 48~921 & 876   &  6762 & V\'eron-Cetty \& V\'eron (\cite{veron03}) \\
 85~221 &1122 &  9628 & V\'eron-Cetty \& V\'eron (\cite{veron06}) \\
133~336 &1374 & 16~517 & Present edition                         \\
\hline 
\end{tabular}  
\end{table}