This page provides a detailed breakdown of how IPv4 address space is distributed across each /8 block. These delegations include allocations, assignments, and legacy registrations of various statuses.
By analyzing the concentration of prefix sizes, researchers and operators can identify where address space is heavily fragmented versus more contiguous. This data can also help establish "cut-off" points when filtering based on the minimum allocation size.
For more background information see the RIPE Labs article.
Data is based on the RIR stats files of the five Regional Internet Registries: