A hint to "the code"

Code for gifts:
0, 8, 18 or 19, 20, 22

Yesterday's hint:  The numbers do not put the kids in order.

Clue(s) for today:
This is most likely the ONLY year we can use these numbers or even this code.
The number will change for 3 of the 5 kids eventually.  Actually, I take that back.  The number will increase one final time for the other two kids as well ...