Jim,
I've noticed that chips with an issue date as such, 12/15/15 will not show up using just a 2015 query.

I tested it with the Johnny Z's Halloween and Christmas issues. Most of them have been entered with month/day/year.
Because of that, they do not show up with a 2015 query

Also, using just the "chips" query will only give partial results. One must also use the "chips-all" and "limited edition chips"

Paul