\begin{table}%t1
%\begin{center}
\par
\caption{Number of 1-h data sets for each time series, and 
the monthly spot number at the time of each series (SIDC, 1996--2006). }
\label{tabdata}
\begin{tabular}{ccc}
\hline \hline
Time series & \# Hourly sets & Spot number \\ \hline
August 1996 & 35 &  14.4    \\
January 1997 & 40 &   5.7   \\
March 1997 & 14 &   8.7   \\
April 1998 & 29 &   53.4   \\
October 1999 & 33 &  116.7    \\
October 2000 & 38 &  99.4     \\
February 2001 & 31 &   80.6    \\
December 2002 & 25 &   80.8   \\
May 2003 & 45 &   54.6   \\
May 2004 & 53 &    39.3   \\ 
September 2005 & 21 &   21.9     \\
July 2006 & 87 &   12.2   \\ \hline
\end{tabular}
%\end{center}
\par
\end{table}