\begin{table}[h]
\begin{center} {\footnotesize
\begin{tabular}{|c|cc|cc|cc|cc|}
\hline
 & \multicolumn{2}{c|}{$x=10.3$} & \multicolumn{2}{c|}{$x=10.5$} &
\multicolumn{2}{c|}{$x=21.7$} & \multicolumn{2}{c|}{$x=22.8$} \\
$q$  & \multicolumn{1}{c}{gmt} & \multicolumn{1}{c|}{jfk} &
\multicolumn{1}{c}{fbi} & \multicolumn{1}{c|}{mac} & \multicolumn{1}{c}{fax} &
\multicolumn{1}{c|}{era} & \multicolumn{1}{c}{ibm} &
\multicolumn{1}{c|}{pdf}\\\hline
$a/20$ &     117.01 & 117.02  &   318.31 & 318.27  &   29.83 & 29.85    & 36.35 
& 36.40 \\
$d/40$  &     338.88 & 338.03  &   53.34 & 53.31  &  97.29 & 67.24 &   26.74 &
126.52 \\
$5e$ &     246.58 & 246.50  &   47.57 & 47.57  &  24.28 & 24.89 &   55.54 &
155.26 \\
$7f$    &     157.64 & 157.54  &   36.83 & 36.83  &  38.80 & 38.02 &   72.63 &
172.60 \\
$2g/3$   &     58.08 & 58.05  &   27.35 & 27.32  &  56.20 & 56.23 &   95.47 &
195.49 \\
$\lceil \log h \rceil h^2$    &     18.99 & 18.99  &   99.00 & 98.99  &  58.94 &
158.99 &   98.99 & 98.99 \\
\hline m.t. &     4.6 &  5.1 &     3.8 &  4.1 &     2.2 & 1.9  &   3.6 &  3.7 \\
\hline
\end{tabular} }
\end{center}
\caption{\footnotesize Number of turns and distance between top and bottom.}
\label{turns}
\end{table}