I want to create a plugin that will count the blogging frequency by month. I want to use this among my blogging friends which in the end of the year we gonna reward the person who have the highest blogging frequency.

The formula is as the following:

P=(T-t)/(M-1)

where as

T=total posts

t=total posts of the current month

M-total months from the first post until the current month

For example,

Blog A have 174 posts in total since June 2006 up until today, Jan 2007. In January alone, there are 4 posts. Hence,

(174-4)/(8-1)=24.2857143points

Can anyone help with what functions to call?

Thank you in advance