Board Thread:General Discussion/@comment-10773451-20130724175203/@comment-4747848-20130915140815

Just to clarify everything, I believe you have to wait 4 years for it to become rare. For instance, the 4th year party hat:

2009 (released) --> 2010 (quite common) --> 2011 (uncommon) --> 2012 (more uncommon) --> 2013 rare

Hope this helps.

NOTE: Don't add items as soon as it becomes any year; wait until the exact date!