Joost de Valk have created a nice little API to provide us, a graphical chart for displaying the Feedburner Circulation Data (Well as to my knowledge is how much subscribers you have, somethin like that)
Using the FeedBurner Awareness API, you can extract the circulation data for a blog for a given period of time. If you do this for the last year, you can draw a nice graph of how your RSS subscribers have progressed over the years.
The results (which is dynamic, since it's an API ^^) will looked like this:
Yes, you can have it embeded in your page ;) Joost de Valk is kindly provided the code for us ;)
If you're having trouble with the Graph, then check out his explanation at the bottom of this page ;)