I don't want to be rude and keep you in suspense, so here goes.
First off, the posts per day stat is a simple total posts/number of days registered.
The fact that you got tripped up after that amazes me.
But I have 9 or or so more posts per day than you. We've both been members for how many years, 5? So that is 1800+ days, roughly 18,000 posts. Then I was a member for a few months before you were, so multiply 31 by the number of days I was a member before you were and you'll come up with the full difference between my post count and your's. I don't even want to know how you came up with you 1080 figure. lol.