Population Report (Pop Report)
A database maintained by grading companies showing how many copies of each card have been graded at each grade level. PSA's Pop Report is the most widely used.
A population report tracks every card a grading company has authenticated and graded. It shows the total number of copies graded at each grade level (PSA 1 through PSA 10) for every card in their database.
Population reports are crucial for determining scarcity and value. A card with a PSA 10 population of 5 is exponentially more valuable than the same card with a PSA 10 population of 5,000. The pop report helps collectors distinguish between cards that are genuinely scarce and those that merely appear scarce.
PSA's Pop Report (psacard.com/pop) is free and the most comprehensive. BGS, SGC, and CGC also maintain population reports but with varying levels of public accessibility. Third-party services like GemRate aggregate population data across all grading companies.