Well, let me start off with that I am still very young on this board, and after reading this thread this morning, I thought about it all day, and decided to reply
Declawing is a very controversial topic, the same with circumcision(as someone mentioned female circumcision) and so many other topics.
I would personally never ever declaw my cats, unless it was medically necessary. I would never rent an apartment if I was told that my cats have to be declawed. So to answer your original question: 0 paws are declawed.
Although I have to add, that I have met cats who have been declawed and they were happy well adjusted cats, I didn't notice any psychological damage left behind from the declawing, but as far as I know those cats were really young when the procedure was done.
Declawing is something, that we need to educate others about. There are so many out there, who have no idea how it's done, or what is done exactly, they just know that the cat won't have any claws and that this will safe their furniture. The vets don't tell them, and there are many vets out there I am sure, who advise owners to do it. (my vet doesn't declaw). So if people don't have the info and don't research themselves it's difficult to make a well educated decision. But this is just my opinion, so I can see how someone would come to the decision to declaw their cats.
Like the female circumcision was mentioned in Africa, most people there don't have the information, and are not educated on why it's bad and unnecessary. Mothers take their baby girls to get circumcised, nobody is forcing those mothers to do it, they do it on their own, because that is what they were thought and told to do, they had it done so they take their children to get it done as well. And it's women circumcising women. There are many groups and organizations there that are trying to change people's minds about this totally unnecessary and disfiguring procedure, but there are still many older women who perform it if they are asked to. This is sad, but one small step at a time, with educating and showing people data why it's bad, more and more young mothers chose not to put their children trough the pain that comes with this procedure.(and the numerous health risks)
And it's not only female circumcision but male as well. I am european, and where I come from, men arent' circumcised. 8 years ago when we came to canada I was surprised that men were circumcised here. And it was even more surprising that women thought that it was more "clean". That is something that I just won't understand either. Why do that to a baby? and even today??? that is just as barbaric as female circumcision(yet somehow so accepted) These are nothing else but mutilation of a body part, just like declawing.
So back to the point, as long as vets perform this procedure without telling the pet owners what is being done and the risks, we can't expect much change. I think it's awsome that there are sites that give information on this procedure so people can research for themselves, also sites like this one, where knowledgable poeple who have already done the research provide links and their opinion on this issue.
I can just hope, that knowing what you know now, you wouldn't declaw your cats if you could do it all over again. But then again we can't change a persons opinion, we can only provide them with resources and information and hope that based on those they at least consider and explore other options before taking such drastic measures.