APNIC provides an overview of unused IPv4 address space

The Asia Pacific Network Information Centre (APNIC) conducted an analysis of the pool of allocated but unadvertised Internet Protocol version 4 (IPv4) address space. The analysis revealed that there were 350 000 unadvertised IPv4 addresses delegated less than five years ago; around 50 million unadvertised IPv4 addresses delegated over five years ago; and around 3.4 million unadvertised and returned historical IPv4 addresses. A few of the potential actions imagined by APNIC include returning them to the original pool, transferring them, or having them managed under the APNIC account.