\begin{table}[]
\centering
\rowcolors{2}{lightgray!40}{}
\caption{}
\begin{tabular}{c c c c}\rowcolor{lightgray} 
Parameter & PopED & NONMEM & Pumas \\ 
$\mu_{ka}$ & 4.8 & 4.8 & 4.8 \\ 
$\mu_{Cl}$ & 3.6 & 3.6 & 3.6 \\ 
$\mu_{V}$ & 2.6 & 2.6 & 2.6 \\ 
$\omega^2_{ka}$ & 26.5 & 26.5 & 26.5 \\ 
$\omega^2_{Cl}$ & 26.3 & 26.3 & 26.3 \\ 
$\omega^2_{V}$ & 30.9 & 30.9 & 30.9 \\ 
$b^2$ & 12.4 & 12.4 & 12.4 \\ 
\end{tabular} 
 label{tab:} 
 \end{table}