Meh. This '76Mb/s' malarky never was a sensible idea to my mind. At least 'up to 80Mb/s' is an accurate, factual statement. The service that openreach provide on their cabinets supports sync speeds up to 80Mb/s.
All people ever needed to understand was that the actual connection speed that they as individuals would see depended on their particular telephone line. But as I mention below that's only part of the story and maybe not a very useful part either, at least as far as advertising and comparing ISPs is concerned.
The '10% must have achieved..' is pointless. So what if 10% of UK FTTC enabled telephone lines achieve 76Mb/s. It means nothing to an individual customer. Maybe they are in the 10%, maybe they are outside it. Just because someone in Chipping Sodbury gets a fast connection says nothing about the hopes and aspirations of someone in Leamington Spa.
The worst of it is that no ISP other than VM can do anything about that figure anyway. The laws of physics and physical infrastructure mean that your line gets what it gets and it'll be the same for all ISPs (excluding VM as noted above). Ironically the one throughput figure an ISP can affect (peak time throughput) is something that no-one quotes and Ofcom never bothers about. Your 'up to 76Mb/s' line may only be running at 80% of capacity at 8pm because your ISP can't get the data to you any faster but there's little to no official support for complaining about that. Likewise if their interlinks are poor there's no help with that.