\begin{table}[]
\centering
\rowcolors{2}{lightgray!40}{}
\caption{}
\begin{tabular}{c c c c}\rowcolor{lightgray} 
Parameter & PopED & NONMEM & Pumas \\ 
$\mu_{ka}$ & 8.6 & 8.6 & 8.6 \\ 
$\mu_{ke}$ & 6.9 & 6.9 & 6.9 \\ 
$\mu_{V_d}$ & 8.4 & 8.4 & 8.4 \\ 
$\mu_{EC_{50}}$ & 13.5 & 13.5 & 13.5 \\ 
$\mu_{n}$ & 7.5 & 7.5 & 7.5 \\ 
$\mu_{\delta}$ & 8.5 & 8.5 & 8.5 \\ 
$\mu_{c}$ & 8.7 & 8.7 & 8.7 \\ 
$\omega^2_{ka}$ & 43.1 & 43.1 & 43.1 \\ 
$\omega^2_{ke}$ & 37.1 & 37 & 37.1 \\ 
$\omega^2_{V_d}$ & 33.1 & 33.1 & 33.1 \\ 
$\omega^2_{EC_{50}}$ & 66.3 & 66.3 & 66.3 \\ 
$\omega^2_{n}$ & 33 & 33 & 33 \\ 
$\omega^2_{\delta}$ & 31.6 & 31.6 & 31.6 \\ 
$\omega^2_{c}$ & 33.5 & 33.5 & 33.5 \\ 
$a^2_{PK}$ & 8.4 & 8.4 & 8.4 \\ 
$a^2_{PD}$ & 9.2 & 9.2 & 9.2 \\ 
\end{tabular} 
 label{tab:} 
 \end{table}