User Adoption Industry Benchmark

There aren't these kind of benchmarks that currently exist primarily because each company is different in what it terms success in its usage of Office 365.  In my Service Adoption Specialist course I detail 4 areas where KPI's should be designed to ensure business value from O365 deployments: Organizational, Cultural, Tangible and Individual.  If you follow the announcement to that course you can find more information there.  https://aka.ms/AdoptionCertAnnouncement

I'd suggest benchmarking your success to your own  business objectives to get the best value.