When I did this, it was using free software and knowing very little programming language. If anyone who knows more about computer programming than me (which is probably all of you) and wants to help out on this project, I would love to find a way to better keep track of these totals.
That being said, here is a quick and dirty run through my model.
If you have any questions, or would like me to go further into any part of the model, please let me know and I will try another screen-cast. I have also meet several times on Google hangouts or Skype with interested parties.