there are 2,890,758 P's
there are 2,890,758 D's
and 3,227,194 S's
but according to my Redbook non were issued for circulation.
so the only thing rare is the fact somone decided to spend theirs.
My guess Some who are addicted to SLOT MACHINES
decided they needed to play more then Save,
Some from Thefts
and Some just because they will never really be worth much (Their Clad)