[Retric]

“data showing at least 1 unit sale over the last 52 weeks coming from publishers of all sizes, including individuals.”

“Collectively, 45,571 unique ISBNs appear for these publishers in our frontlist sales data for the last 52 weeks (thru week ending 8-24-2022).“

Both descriptions mean books sold for 1 of the 52 weeks would be included. You would need to see how quickly sales spike and fall off to see how much those statistics underestimate sales over a books first year. Similarly they cover 16,000 retailers, however it could be some of these books like say textbooks are primarily sold outside of these channels.