"Day" should be thought of as "ICO Window". Window 0 is 5 days long and includes 200,000,000 tokens. Each other window is 1 day and includes 2,000,000 tokens. You can view the code to see that.
This first window will set the prices from here own.
Each window has it's own price mechanism. It's simply 2,000,000 divided by the amount contributed for that window.
it should be total contributed divided by total tokens,
If you just want the total price overall, but I'm more interested in the individual ICO windows which each have their own price based on the contribution for that window.