I was hoping ThirdStats would show the details of how many mails per day/week/month/year, but the counts are always wrong.

Currently, ThirdStats claims I'm getting 9.2 emails per-day in the last 1 month.

But looking at Thunderbird directly, the counts are significantly higher than that:

I've dumped the cache, re-built, tried a new profile and so on, all with the same results.

How can I get ThirdStats to show accurate statistics?