Dodgy-looking stuff in graph calculations

I noticed that the graphs in this post - https://forum.pfsense.org/index.php/topic,72794.0.html - had numbers for in-block and out-block that had similar numbers to in-pass and out-pass. That seemed hard to believe. Found these calculations that look wrong.
Merge pull request #939 from phil-davis/master

Dodgy-looking stuff in graph calculations