I dont think there are any stats. I tried to compile stats some time ago but I faced the attitude of people who 'control' the hierarchy of the waterways. It was clear they did not want change. I could go deeper than this but then I will risk the ire of some at the expense of their misunderstanding of how the equations work.
As for the other question, I dont think it is a issue of what we would like to see, because much of it actually comes to an extent from fairly simple common sense and observation. There is one big issue, and that is there is a difference in opinion as to what should be provided because one kind of provision can easily be another person's barrier. But if we can see that there is an effort to make some sensible provisions, we can also help to ensure that it is the most sensible approach that is used, thus lessening any potential conflicts for users.
I think there is a massive historical misperception that encourages an idea of not wanting changes to the waterways. But the utterly, most ironic leverage, in this matter is that the waterways end up shooting themselves in the foot. For the waterways were made quite wholly accessible from the very beginning. Even later canals had beautifully level towpaths, innnovative bridge designs, the lot. Why is this?
Look at ramps, turnover bridges, etc. The canal engineers built comprehensive accessibility across the canal system. Their graceful structures and innovative designs were amazing. It was an amazing project that was conceived by the canal engineers, for a different type of mobility. That was the boat horse. Of course it was to help waterways operations work smoother, which is the point most people tend to look at. But if we discount that perspective then we are looking at an amazing design that was incredibly innovative. This has been lost to quite an extent through historical destruction and historical ignorance. If it had been people bow-hauling the canal boats, I do not think there would have been such comprehensive provision, because for example where bow-hauling existed the towpaths were usually not of such good design.
The paradox is that people seem to think that there shouldnt be any changes to the waterways for disabled users. One of my arguments, which has been lost on a lot of people, is that we are simply taking the waterways back to what they were before. Which is what I thought was what people wanted. Ah, the problem is, when 'disability' comes into the factors, people dont really want to know. They'd rather not see changes. But its so prelapsarian because it harks back to an age that in fact doesnt exist, whilst denying an age that actually existed, but wiped off canal history. Its just the old attitude towards disability, the more hidden it is, the better.