How to show number of posts next to categories?

I’ve seen lots of wordpress blogs that actually show the number of posts in a given category in the categories widget, but for some reason the mystique theme i have installed isn’t doing this. Where can i go in the code to add this feature or how can i add it? For example, a blog might have under the categories widget “Flowers (11)” showing that there are 11 posts in the Flowers category. Any ideas on how i can enable this on the mystique theme?