\begin{table}%t1
%\centering
\par
\caption{Results of the past campaigns of observations.\label{tab1}}
\small
\begin{tabular}  {llll}
\noalign{\smallskip}
\hline
\hline
\noalign{\smallskip}
    &1985 &1991 &1997\\
\hline
\noalign{\smallskip}
  Number of sites           &28 &56 &42   \\
  Number of light curves    &166 &374 &275  \\
  Number of observed events &64 &111 &148 \\
\noalign{\smallskip}
\hline
\end{tabular}
\end{table}