Dynamic Banner changing

[admin]

There are three banners at my website.One at the top,one at the bottom and one in the side.
I wish that

For Top Banner
If there are two banners banner and banner2
I want it in such a way that banner2.html shows up atleast 600,000 times a day and then

banner.html shows up the rest of the time.

For side banner
If there are two banners Sky and sky2 then sky2.html should show up 700,000 times a day and

then sky.html should show the rest of the times.

For Bottom banner

If there are two banners block and block2 then block2.html shows 700,000 times and

block.html shows the rest of the times.


How can I do that using Java Script Code? Can any one help me?