\begin{table}[]
\centering
\rowcolors{2}{lightgray!40}{}
\caption{}
\begin{tabular}{c c c c}\rowcolor{lightgray} 
Parameter & PopED & NONMEM & Pumas \\ 
$\mu_{ka}$ & 4.2 & 4.2 & 4.2 \\ 
$\mu_{Cl}$ & 4 & 4 & 4 \\ 
$\mu_{V}$ & 4.3 & 4.3 & 4.3 \\ 
$\beta_{Cl, Treat}$ & 21.9 & 21.9 & 21.7 \\ 
$\beta_{V, Sex}$ & 21.2 & 21.2 & 21 \\ 
$\omega^2_{ka}$ & 41.9 & 41.9 & 41.7 \\ 
$\omega^2_{Cl}$ & 26.5 & 26.5 & 26.5 \\ 
$\omega^2_{V}$ & 32.4 & 32.4 & 32.3 \\ 
$\gamma^2_{ka}$ & 51.7 & 51.7 & 51.1 \\ 
$\gamma^2_{Cl}$ & 24.4 & 24.3 & 24.3 \\ 
$\gamma^2_{V}$ & 36.7 & 36.7 & 36.7 \\ 
$a^2$ & 10.6 & 10.6 & 10.6 \\ 
\end{tabular} 
 label{tab:} 
 \end{table}