Automatic three digit grouping

I have huge numbers in tables (some of them are grouped in three digit groups but some are not).

I need to make a small space (or comma) between groups of three digits. I have used two packages

\usepackage{numprint} and \usepackage{siunitx}

But it doesn't show any changes in my tables.

I know I can do manually using the backslash but I have heaps of numbers in my tables.

Here my code,

\begin{tabular}{|l|l|l|}
\hline
x & y & z \\ 
\hline
9,833.823 & 550,245 & 15004568 \\ 
\hline
9,458.230 & 81,345.23 & 198000344 \\ 
\hline
\end{tabular}