how to count the future posts within category

Hi I’m hoping someone is able to help.

I’m running an events site and its set up to display all future posts within each category. However when i count the number of post within each category it displays past posts and not the future posts.

<?php
$variable = wp_list_categories('echo=0&show_count=1&hide_empty=0');
$variable = str_replace('(', '<span class="post-count">Posts: ', $variable);
$variable = str_replace(')', '</span>', $variable);
echo $variable;
?>

Does anyone have any ideas how i count the future posts?

Thanks