egyptor

I am a statistics major in undergrad and found that this graph was extremely interesting. But logically, it would make sense that this would be so.
People who have a Comcast email would be paying for their address. If they fail to make payments, the account is terminated (at least as far as I'm aware)...meaning that these people better have good credit or else they can't use their account.
Furthermore, everyone who uses GMail more or less switched to it from either hotmail or yahoo (stated in a simpler manner, those who use GMail made a choice, whereas those using Yahoo were just grandfathered in). People who changed over (including me) had a huge incentive IF they understood what their email account stats meant. I.e. what if someone doesn't understand what the difference between a MB and GB is? Why would ANYONE change over from 5MB (yahoo at the time) to only 1GB (Initial GMail).
Lastly, I rarely trust yahoo. Why would I? Almost all the "Nigerian scam" email I've ever either from Yahoo or some random server name, only a few from hotmail, and I've yet to see any from GMail. Still furthermore, maybe the lower score for Yahoo users (on average) is due to those who are more likely to fall for scams being on that service.
Of the 20 people I most commonly email, every single one is either using GMail or have their own Google apps service (meaning, they're still using Google).
Lastly, I wish this included age gradients. I'd expect that those ~20-ish would be mostly GMail, ~50+ would be mostly yahoo/AOL. The rest would be sprinkled about.
This isn't to say that there are NO exceptions...I'd just say a trend.