Origin.
Industry consensus, documented across local-SEO research firms, puts the inquiry volume advantage of top-3 map-pack positions at 93% over positions 4 to 10. The advantage is not gradual. A contractor at position 3 receives a multiple of the inquiries a contractor at position 4 receives. The drop is a cliff, not a slope, because the user interface itself collapses positions 4 through 10 into an “Expand More Places” menu that most users never open.