Perhaps it's surprising (for us) , why partly a commemorative note appears to a bent birthday.
The fact is, that some birthdays were counted in the 12th cycle. Sixth cycle birthday = 72nd birthday.
Then, however, at the same moment there is also to a round birthdays a commemorative issue.
To the view click on the wished Commemorative Banknote
Some of the Commemorative Banknotes are given in folders - to the view click on the folder