I kind of feel let down reading the OP.
After all those stats, I was hoping there would be something like "...and we went another year without Muse DLC and survived".
It's not all about Muse. I mean, I get that you're mostly kidding, but still. There were <looks up> 100 other bands that came out this year.
Okay, made a couple of edits, including reducing the number of pro guitar releases by 1. I had gone out on a limb and assumed that Andrew W.K.'s "Party Hard" would get pro-ified, but alas, no such luck.
I have a question about the "Previously Only on a RB Title, Finally DLC" section.
Shouldn't Sum 41 be listed up there under Lego RB?
There are now 29 artists (including the Sounds) in Rock Band 3 that have had no DLC released.
Why do The Sounds merit special mention?
Is "2112" by Rush considered 2012 or 2011? It came out in 2011 (Dec. 31) on 360, but in 2012 on PS3 (Jan. 3, full version not available on Wii).
XBL release = Official release date for songs. With I think 1 exception when the PS3 actually got something first due to XBL maintinance.