Four sets for this year.
Set C1-C16 has blue fronts and yellow backs.
Set E1-E16 has yellow fronts and orange backs.
Set S1-S16 has purple fronts and yellow backs.
Set W1-W16 has red fronts and green backs.

There are four regional sets, north south east and west. For some odd reason, they used Roman numerals on the disks for numbering.