\begin{table}%t2b
\caption{The frequency distribution of $\Delta\delta$.}\label{tab2b}
%\centerline
{
\begin{tabular}{ c c cccccccc }
       \hline \hline
 ~~~ & $|\Delta\delta|$($0''.01$) & 00--7.5 &7.5--15&15--22.5&22.5--30
     &30--37.5&37.5--45&45--52.5&~~$>$52.5\\
       \hline
 Hipp        &  N  & 2204  & 1031  & 386  & 189  & 73 & 49 & 20  & 0  \\
 ~           & \%  & 55.7  & 26.1  & 9.8  & 4.8  & 1.8& 1.2& 0.5 & 0  \\
 CAMC4       &  N  &  81   &  53   &  61  &  42  & 29 & 15 & 17 & 31  \\
 ~           & \%  & 24.4  & 16.0  & 18.4 & 12.7 & 8.7& 4.5& 5.1& 9.3 \\
       \hline
 \end{tabular}}
\medskip
    From Tables~\ref{tab2a} and~\ref{tab2b}, we can see that the position corrections  for about
 $97.7\%$ and~$96.4\%$ of the Hipparcos stars are less than 20~ms
 in $\Delta\alpha$ and~$0.30''$ in~$\Delta\delta$ respectively.
\end{table}