It’s been getting “more and more use” since 2001. To start with the isps said that they were not going to do any work to implement it until endpoints supported it. Then vista came with support by default. Next they wanted the backbones to support it. All tier 1 networks are now dual stack. Then they said they were not going to do anything until websites supported it widely. Now all cdns support it. Then they said, it’s ok we will just do mass nat on everyone so won’t do any work on it.