Hello,
As posted by @calinbehtuk, you need to use
<?php $item = Stats::newInstance()->items_by_user(); ?>
.
It returns an array, what interests you is $item[0]['avg'].
So to get the average listings by user rounded to 2 decimals use this code:
<?php
$item = Stats::newInstance()->items_by_user(); // Get stats array.
$average = $item[0]['avg']; // Get average items from array.
$average = number_format($average, 2); // Round.
printf( __('%s listings per user'), $average ); // Output (with translation).
?>
Regards.