\begin{table}%T1
%\centering
\par
\caption{List of measurements of CH$_4$ abundances in Saturn's atmosphere published since 1981.}\label{CH4}
  \begin{tabular}{ccccc}
            \hline
            \hline
          \noalign{\smallskip}
    CH$_4$/H$_2$ ($\times$$10^{-3}$) & Solar enrichment &  Reference & Measurement  \\
   \noalign{\smallskip}
  \hline
    \noalign{\smallskip}
    2 $\pm$ 0.5 & 3.4 $\pm$ 0.9 & Kerola et al. (\cite{Kerola97}) & KAO  \\ 
    $2^{+1.0}_{-0.8}$ & $3.4^{+1.7}_{-1.4}$ & Encrenaz \& Combes (\cite{Encrenaz82}) & ground-based \\ 
    $2.2^{+0.8}_{-0.2}$ & $3.8^{+1.4}_{-0.3}$ & Killen (\cite{Killen88}) & ground-based  \\ 
    2.5 & 4.3 & Tomasko \& Doose (\cite{Tomasko84}) & $Pioneer$ IPP  \\ 
    3 $\pm$ 0.6 & 5.2 $\pm$ 1.0 & Karkoschka \& Tomasko (\cite{Karkoschka92}) & ground-based  \\ 
    4 $\pm$ 2 & 6.9 $\pm$ 3.4 & Buriez \& de Bergh (\cite{Buriez81}) & ground-based \\ 
    4.2 $\pm$ 0.4 & 7.2 $\pm$ 0.7 & Trafton (\cite{Trafton85}) & ground-based  \\ 
    4.4 $\pm$ 1.2 & 7.6 $\pm$ 2.1 & Lellouch et al. (\cite{Lellouch01}) & ISO-SWS  \\ 
   $4.5^{+2.4}_{-1.9}$ & $7.7^{+4.1}_{-3.3}$ & Courtin et al. (\cite{Courtin84}) & $Voyager$ IRIS  \\ 
    5.1 $\pm$ 1.0 & 8.8 $\pm$ 1.7 & Flasar et al. (\cite{Flasar05}) & $Cassini$ CIRS  \\ 
  \hline
     \end{tabular}
\end{table}