A couple comments.
For one, I a struck by how some settings that loom large in our collective minds have actually had relatively short-lived, or sparse, support. Birthright stands out - just four years. And even Dark Sun, Eberron, and Planescape - they were really only significantly supported for five (Planescape), six (Eberron), and seven (Dark Sun) years at a time, with bits and pieces after.
I'm probably going to start a separate thread about this, given I am genuinely curious, but I wonder how common the view is that Birthright looms large in the collective D&D mind.
So all that is pending revision.
First, thank you. Please don't view what I am going to write as criticism, at all. Anytime someone chooses to take on a project like this, it's going to be a rough one ... no matter how much you know about all the settings, you won't know as much about any given setting as some person who has spent decades tending the Forgotten Realms wiki (for example). And fans of every setting will be pushing to have their settings get coded for more years (Hey, remember when there was an on-line mention by WoTC of my favorite setting in 2007? THAT COUNTS! PUT IT ON THE SCOREBOARD!!!!!).
So you have my sympathy, as well as my thanks for taking this on!
With that said, I would make the following recommendation and obsevations:
Recommendation: As Snarf, I am duty-bound to recommend that you put in some more
rules or you will be facing madness. Especially when it comes to the "light" part- for example, I think you probably need to be clear that to qualify for a "light box," it has to be a published product that primarily, or mostly, takes place in the setting. A module, adventure, or other official published product that isn't a major campaign update or regional guide etc. (dark and medium).
And decide if you want to include Dragon Magazine. I'd say ... no. Or code it differently. Because once you include Dragon (and or other semi-official sources) you're going to go the direction of madness. IMO.
Observations:
1. Forgotten Realms did not exist in D&D until the Gray Box. Yes, Greenwood was in Dragon prior to that, but if you're including Dragon you're going to run into a lot of issues. You will end up with a lot of boxes shaded from the 70s through the 00s, and lose a lot of the value of your chart.
2. There are some curious omissions I noticed when going over this; for example, Kara Tur had a series of modules published from '86-'89 that you would want shaded in (the OA series).
Overall, though, this is excellent and clearly researched well. I appreciate that you even incorporated the "Greyhawk hole" from '94-'97 (although hardcore fans would argue that the AOL release of Ivid the Undying would count .... AOL......).