Only Show Categories with More than 1 Post

I have about 1,000 categories on my site. Most of them only have 1 post apiece, but the important categories have multiple posts.

Can anybody think of a way to display only those categories that have greater than 1 post?

Here’s the calling code in the sidebar currently showing all categories:

<div class="sidebar-box">
<h3><?php _e('Categories'); ?></h3>
<ul class="list">
<?php wp_list_categories('orderby=slug&show_count=1&use_desc_for_title=0&title_li='); ?>
</ul>
</div>