Necessitating change is that the site's Canon serial number to manufacturing date conversion chart has been falling apart in 2013.
First, I'd like to say "Thanks" to all of you who let me know that your new lens was manufactured at some future date. :) While I jest, I seriously appreciate those of you who did provide that information.
We've been researching the necessary corrections. With your help and with the help of Lensrentals.com, I have updated the Canon Lens Date Code Chart
While I'm not positive that the new numbers are 100% accurate, they are definitely better than before. And with your help, we will continue to dial them in to perfection (if perfection is indeed possible).