Help with show_count

Hi to all!

I want to show number of posts of each category in my menu. I’m using a drop down menu but I want to show number of posts only for subcategories, while next to parent category I don’t want to show number of posts. How to remove show_count only from parent category?

And I want to customize a little bit this number. Currently, it’s displaying as (number) but I want to display it as <span>number</span>. I tried this code:

<?php
$categoryshow = wp_list_categories('sort_column=name&sort_order=asc&style=list&show_count=1&children=true&hierarchical=true&title_li=0');
$categoryshow = str_replace( '(', '<span>', $categoryshow);
$categoryshow = str_replace( ')', '</span>', $categoryshow);
ech

but it doesn’t work. There are still ( and ) and no <span> or </span>. Why??

Thank you in advance!