User sign-up rate?

@Moderators:

Subjectively it appears the sign-up rate for this forum is growing rapidly. Do you track the rate of growth? Is it exponential now? Is the growth "normal" for a forum of this age? Or is the world waking to MMS? A graph of the sign-up might look very interesting. (in your spare time - of course )

We recently instituted the captcha and then later the re-captcha software to avoid spam - this has relieved the forum owner from the rather time consuming double email process of approving new members. It has also made it easier for people to join. That may be what is affecting the bump in numbers.