Philadelphia Mint Errors.

They only make coins if they are needed. Some years needed less coins and some none at all. Just depends on demand. Sometimes they mention they are making less coins and more of them are saved in BU rolls. Other times the collectors don't catch on they are making less or no mint sets. So demand is higher when this happens. But most of the time, we don't know it for years afterwards. The ones that do figure it out, hoard them until everyone else missed it.

Compare mintage figures and you will find that umtil the late 1960's typically the Philadelphia mint made considerably more coins than the other mints did each year. More coins, more dies, greater rush, more chances for errors.

If you mean a published reference, No. But you might be able to assemble a partial one by researching through the mint records in the National Archives. Nice long term retirement project.