IMPORTANT NEWS: The chart is getting a ten slot extension, as of the first charting week of 2013 (which was four weeks ago
). So now, the countdown will have an additional 41-50 section that will include what would have been shown in the Bubbling Under. There will also be a section for songs that are bubbling under, but it will not be an ordered set. This is really only to show what is on deck for future chart inclusion, rather than "ranking" what was almost able to make the top 40/50 cut.
Because of this, in addition to the expected 10 song turnover from the Holiday playlist going out of order, there will be 17 debuts and 4 re-entries.