The colored bars represent calendar years, from 2008 till 2015. This one shows everyone who appears more than 18 times (the image is a bit too long XD).
Well, I hope you guys like it.

EDIT:
Note: These kinda counts the guest comics too. Different Versions of Characters are kinda separate (like puppy Peanut, imagine king or a better example, Joel)
Here's an alternate infographic colored based on an HP year (June to May) https://dl.dropboxusercontent.com/u/453 ... y2-hpy.png
And the same one for the earlier and later half.











