1956 Topps Pop Report Question

Has the PSA pop report always differentiated between the white and gray backs? There appears to be some very low pop white back variations between 100-200, and I want to make sure PSA didn't just start tracking these recently. Thanks in advance.
Registry Sets
"Common sense is the best distributed commodity in the world, for every man is convinced that he is well supplied with it"
"Common sense is the best distributed commodity in the world, for every man is convinced that he is well supplied with it"
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Donato
Donato's Complete US Type Set ---- Donato's Dansco 7070 Modified Type Set ---- Donato's Basic U.S. Coin Design Set
Successful transactions: Shrub68 (Jim), MWallace (Mike)
"Common sense is the best distributed commodity in the world, for every man is convinced that he is well supplied with it"